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PostgreSQL iin Ska Sorulan Sorular (SSS)
Son gncelleme : 19.05.2003 Cuma 05:03
Bruce Momjian (pgman@candle.pha.pa.us)
eviren : Devrim GNDZ (devrim@gunduz.org), Nicolai Tufar (ntufar@yahoo.com), Volkan Yazc (volkany@celiknet.com)
Bu belgenin en gncel hali, http://www.gunduz.org/seminer/pg/FAQ_turkish ve
http://www.PostgreSQL.org/docs/faq-turkish.html
adreslerinde gorlebilir.
Platforma zel sorularnz,
http://www.PostgreSQL.org/users-lounge/docs/faq.html adresinde yantlanr.
_________________________________________________________________
Genel Sorular
1.1) PostgreSQL nedir? Nasl okunur?
1.2) PostgreSQL' in haklar nedir?
1.3) PostgreSQL, hangi Unix platformlarnda alsr?
1.4) Hangi Unix olmayan uyarlamalar bulunmaktadr?
1.5) PostgreSQL'i nereden indirebilirim?
1.6) Destei nereden alabilirim?
1.7) En son srm nedir?
1.8) Hangi belgelere ulasabilirim?
1.9) Bilinen hatalar ya da eksik zelliklere nereden ulasabilirim?
1.10) Nasl SQL grenebilirim?
1.11) PostgreSQL 2000 ylna uyumlu mudur?
1.12) Gelitirme takmna nasl katlabilirim?
1.13) Bir hata raporunu nasl gnderebilirim?
1.14) PostgreSQL, diger DBMS'lerle nasl karlatrlabilir?
1.15) PostgreSQL'e maddi adan nasl destek olabilirim?
Kullanc/istemci Sorular
2.1) PostgreSQL icin ODBC srcleri var m?
2.2) PostgreSQL'i web sayfalarnda kullanabilmek iin hangi aralar bulunmaktadr?
2.3) PostgreSQL'in grafik kullanc arabirimi var mdr?
Report generator var mdr? Gml sorgu dili arabirimi var mdr?
2.4) PostgreSQL ile iletiimi kurabilmek iin hangi dilleri kullanabilirim?
Ynetimsel Sorular
3.1) PostgreSQL'i, /usr/local/pgsql dizininden baka dizinlere nasl kurabilirim?
3.2) Postmaster'i baslattgmda, Bad System Call ya da core dumped mesaj
alyorum. Neden?
3.3) Postmaster'i balattmda, IpcMemoryCreate hatas alyorum. Neden?
3.4) Postmaster'i balattmda, IpcSemaphoreCreate hatas alyorum. Neden?
3.5) Dier bilgisayarlarn benim PostgreSQL veritaban sunucuma balantlarn nasl
kontrol edebilirim?
3.6) Veritaban motorunu daha iyi baarm icin nasl ayarlayabilirim?
3.7) Hangi hata ayklama zellikleri bulunmaktadr?
3.8) Balanmaya alrken, neden "Sorry, too many clients" hatasn alyorum?
3.9) pgsql_tmp dizininin iindeki dosyalar nelerdir?
3.10) PostgreSQL srmlerini ykselmek iin neden bir dump/reload ilemi gerekletirmek
zorundaym?
letimsel Sorular
4.1) Binary cursor ve normal cursor arasndaki fark nedir?
4.2) Sorgunun sadece ilk birka satrn nasl SELECT edebilirim?
4.3) psql'in iinde grdm tablolarn ya da dier eylerin listesini nasil alabilirim?
4.4) Bir tablodan bir kolonu nasl kaldrabilirim?
4.5) Bir satr, tablo ve veritaban icin en fazla byklk nedir?
4.6) Tipik bir metin dosyasndaki veriyi saklamak iin ne kadar disk alan gereklidir?
4.7) Veritabannda hangi tablo ya da indexlerin tanmlandgn nasl grebilirim?
4.8) Sorgularm cok yava, ya da indexlerimi kullanmyorlar. Neden?
4.9) Query-optimizer in sorgularm nasl deerlendirdigini, ileme soktuunu nasl grebilirim?
4.10) R-tree index nedir?
4.11) Genetic Query Optimizer nedir?
4.12) Dzenli ifade (Regular Expression) aramalarn ve byk/kk harfe duyarsz aramalar nasil yapabilirim?
Bu byk(kk harfe duyarl aramalar iin indeksi nasil kullanabilirim?
4.13) Bir sorguda, bir alann "NULL" olduunu nasl ortaya karabilirim?
4.14) esitli karakter tipleri arasndaki farklar nelerdir?
4.15.1) Nasl serial/otomatik artan(auto-incrementing) bir alan yaratabilirim?
4.15.2) SERIAL giriinin deerini nasl alabilirim?
4.15.3) currval() ve nextval() dier kullanclara sorun yaratmaz m?
4.15.4) Neden sequence saylarn transaction ileminin iptalinden sonra yeniden kullanlyor? Neden sequence/SERIAL
kolonumdaki saylarda atlamalar oluyor?
4.16) OID nedir? TID nedir?
4.17) PostgreSQL' de kullanlan baz terimlerin anlamlar nelerdir?
4.18) Neden "ERROR: Memory exhausted in AllocSetAlloc()"? hatasn alyorum?
4.19) Hangi PostgreSQL srmn alstrdm nasl grebilirim?
4.20) Neden large-object ilemlerim, "invalid large obj descriptor"? hatasn veriyor?
4.21) u andaki zaman ntanml deer olarak kabul eden kolonu nasl yaratrm?
4.22) Neden IN kullanan subquerylerim ok yava?
4.23) Outer join ilemini nasl yapabilirim?
4.24) Ayn anda birden fazla veritabannda nasl ilem yapabilirim?
4.25) Bir fonksiyondan nasl oklu satr ya da kolon dndrebilirim?
4.26) Neden Pl/PgSQL fonksiyonlar iinden gvenli bir ekilde tablo yaratma/kaldrma ilemlerini yapamyoruz?
4.27) Hangi replikasyon seenekleri bulunmaktadr?
4.28) Hangi ifreleme seenekleri bulunmaktadr?
PostgreSQL zelliklerini Geniletmek
5.1) Kullanc-tanml bir fonksiyon yazdm. psql'de altrdm zaman neden
core dump ediyor?
5.2) PostgreSQL'e nasl yeni veri tipleri/fonksiyonlar ekleyebilirim?
5.3) Bir tuple dndrmek iin bir C fonksiyonunu nasl yazarm?
5.4) Bir kaynak dosyasnda deisiklik yaptm. Yeniden derlememe ramen
deiiklik geerli olmuyor. Neden?
_________________________________________________________________
Genel sorular
1.1) PostgreSQL nedir?
PostgreSQL, Post-Gres-Q-L olarak okunur.
PostgreSQL, yeni-nesil VTYS arastrma prototipi olan POSTGRES veritaban
ynetim sisteminin gelitirilmesidir. POSTGRES' in zengin veri
tiplerini ve gl veri modelini tutarken, SQL'in gelitirilmis alt kmesi
olan PostQuel dilini kullanr. PostgreSQL cretsizdir ve kaynak kodu ak datlr.
PostgreSQL, PostgreSQL gelistirme listesine ye olan bir nternet gelistirici
takm tarafndan gelitirilir. u andaki koordinatr, Marc G. Fournier
(scrappy@PostgreSQL.org). (Bu takma nasl katlacagnz grenmek iin
1.6 numaral maddeyi okuyunuz.) Bu takm, tm PostgreSQL geliiminden sorumludur.
PostgreSQL 1.01 srmnn yazarlar Andrew Yu ve Jolly Chen idi. Bunlarn dsnda bir ka kisi de uyarlama,
hata ayklama ve kodun gelistirilmesi iin alsmst. PostgreSQL'in tredigi orijinal Postgres kodu,
lisans, lisansst ve akademisyenler tarafindan, Professor Michael Stonebraker ) University of
California, Berkeley) koordinatrlgnde yazlmstr.
Berkley'deki yazlmm ad Postgres idi. SQL uyumlulugu 1995'te eklenince, ad Postgres 95
oldu. 1996 ylnn sonlarnda ad PostgreSQL olarak degistirildi.
1.2) PostgreSQL'in haklar nedir?
PostgreSQL Data Base Management System
Portions copyright (c) 1996-2002, PostgreSQL Global Development Group
Portions Copyright (c) 1994-6 Regents of the University of California
PostgreSQL için Sýkça Sorulan Sorular (SSS) Son güncelleme : 19 Mayýs
2003 Pazartesi - 03:05:21 Current maintainer: Bruce Momjian
(pgman@candle.pha.pa.us ) Çeviren : Devrim GÜNDÜZ (devrim@gunduz.org )
Nicolai Tufar (ntufar@yahoo.com ) Bu belgenin en güncel hali,
http://www.PostgreSQL.org/docs/faqs/FAQ_turkish.html ve
http://www.gunduz.org/seminer/pg/FAQ_turkish adreslerinde görülebilir.
Platforma özel sorularýnýz,http://www.PostgreSQL.org/docs/index.html
adresinde yanýtlanýr..
----------------------------------------------------------------------
-- Genel Sorular 1.1 <#1.1>) PostgreSQL nedir? Nasýl okunur? 1.2
<#1.2>) PostgreSQL' in haklarý nedir? 1.3 <#1.3>) PostgreSQL, hangi
Unix platformlarýnda çalýsýr? 1.4 <#1.4>) Hangi Unix olmayan
uyarlamalarý bulunmaktadýr? 1.5 <#1.5>) PostgreSQL'i nereden
indirebilirim? 1.6 <#1.6>) Desteði nereden alabilirim? 1.7 <#1.7>) En
son sürümü nedir? 1.8 <#1.8>) Hangi belgelere ulasabilirim? 1.9
<#1.9>) Bilinen hatalar ya da eksik özelliklere nereden ulasabilirim?
1.10 <#1.10>) Nasýl SQL öðrenebilirim? 1.11 <#1.11>) PostgreSQL 2000
yýlýna uyumlu mudur? 1.12 <#1.12>) Geliþtirme takýmýna nasýl
katýlabilirim?? 1.13 <#1.13>) Bir hata raporunu nasýl gönderebilirim?
1.14 <#1.14>) PostgreSQL, diger VTYS(DBMS lerle nasýl
karþýlaþtýrýlabilir? 1.15 <#1.15>) PostgreSQL'e maddi açýdan nasýl
destek olabilirim? Kullanýcý/istemci Sorularý 2.1 <#2.1>) Are there
ODBC drivers for PostgreSQL? 2.2 <#2.2>) What tools are available for
using PostgreSQL with Web pages? 2.3 <#2.3>) Does PostgreSQL have a
graphical user interface? 2.4 <#2.4>) What languages are available to
communicate with PostgreSQL? Administrative Questions 3.1 <#3.1>) How
do I install PostgreSQL somewhere other than //usr/local/pgsql/? 3.2
<#3.2>) When I start /postmaster/, I get a /Bad System Call/ or core
dumped message. Why? 3.3 <#3.3>) When I try to start /postmaster/, I
get /IpcMemoryCreate/ errors. Why? 3.4 <#3.4>) When I try to start
/postmaster/, I get /IpcSemaphoreCreate/ errors. Why? 3.5 <#3.5>) How
do I control connections from other hosts? 3.6 <#3.6>) How do I tune
the database engine for better performance? 3.7 <#3.7>) What debugging
features are available? 3.8 <#3.8>) Why do I get /"Sorry, too many
clients"/ when trying to connect? 3.9 <#3.9>) What is in the
/pgsql_tmp/ directory? 3.10 <#3.10>) Why do I need to do a dump and
restore to upgrade PostgreSQL releases? Operational Questions 4.1
<#4.1>) What is the difference between binary cursors and normal
cursors? 4.2 <#4.2>) How do I SELECT only the first few rows of a
query? 4.3 <#4.3>) How do I get a list of tables or other things I can
see in /psql/? 4.4 <#4.4>) How do you remove a column from a table?
4.5 <#4.5>) What is the maximum size for a row, a table, and a
database? 4.6 <#4.6>) How much database disk space is required to
store data from a typical text file? 4.7 <#4.7>) How do I find out
what tables, indexes, databases, and users are defined? 4.8 <#4.8>) My
queries are slow or don't make use of the indexes. Why? 4.9 <#4.9>)
How do I see how the query optimizer is evaluating my query? 4.10
<#4.10>) What is an R-tree index? 4.11 <#4.11>) What is the Genetic
Query Optimizer? 4.12 <#4.12>) How do I perform regular expression
searches and case-insensitive regular expression searches? How do I
use an index for case-insensitive searches? 4.13 <#4.13>) In a query,
how do I detect if a field is NULL? 4.14 <#4.14>) What is the
difference between the various character types? 4.15.1 <#4.15.1>) How
do I create a serial/auto-incrementing field? 4.15.2 <#4.15.2>) How do
I get the value of a SERIAL insert? 4.15.3 <#4.15.3>) Don't
/currval()/ and /nextval()/ lead to a race condition with other users?
4.15.4 <#4.15.4>) Why aren't my sequence numbers reused on transaction
abort? Why are there gaps in the numbering of my sequence/SERIAL
column? 4.16 <#4.16>) What is an OID? What is a TID? 4.17 <#4.17>)
What is the meaning of some of the terms used in PostgreSQL? 4.18
<#4.18>) Why do I get the error /"ERROR: Memory exhausted in
AllocSetAlloc()"/? 4.19 <#4.19>) How do I tell what PostgreSQL version
I am running? 4.20 <#4.20>) Why does my large-object operations get
/"invalid large obj descriptor"/? 4.21 <#4.21>) How do I create a
column that will default to the current time? 4.22 <#4.22>) Why are my
subqueries using |IN| so slow? 4.23 <#4.23>) How do I perform an outer
join? 4.24 <#4.24>) How do I perform queries using multiple databases?
4.25 <#4.25>) How do I return multiple rows or columns from a
function? 4.26 <#4.26>) Why can't I reliably create/drop temporary
tables in PL/PgSQL functions? 4.27 <#4.27>) What replication options
are available? 4.28 <#4.28>) What encryption options are available?
Extending PostgreSQL 5.1 <#5.1>) I wrote a user-defined function. When
I run it in /psql/, why does it dump core? 5.2 <#5.2>) How can I
contribute some nifty new types and functions to PostgreSQL? 5.3
<#5.3>) How do I write a C function to return a tuple? 5.4 <#5.4>) I
have changed a source file. Why does the recompile not see the change?
----------------------------------------------------------------------
-- General Questions 1.1) What is PostgreSQL? How is it pronounced?
PostgreSQL is pronounced /Post-Gres-Q-L/. PostgreSQL is an enhancement
of the POSTGRES database management system, a next-generation DBMS
research prototype. While PostgreSQL retains the powerful data model
and rich data types of POSTGRES, it replaces the PostQuel query
language with an extended subset of SQL. PostgreSQL is free and the
complete source is available. PostgreSQL development is performed by a
team of developers who all subscribe to the PostgreSQL development
mailing list. The current coordinator is Marc G. Fournier
(scrappy@PostgreSQL.org ). (See section 1.6 <#1.6> on how to join).
This team is now responsible for all development of PostgreSQL. The
authors of PostgreSQL 1.01 were Andrew Yu and Jolly Chen. Many others
have contributed to the porting, testing, debugging, and enhancement
of the code. The original Postgres code, from which PostgreSQL is
derived, was the effort of many graduate students, undergraduate
students, and staff programmers working under the direction of
Professor Michael Stonebraker at the University of California,
Berkeley. The original name of the software at Berkeley was Postgres.
When SQL functionality was added in 1995, its name was changed to
Postgres95. The name was changed at the end of 1996 to PostgreSQL.
1.2) What is the copyright on PostgreSQL? PostgreSQL is subject to the
following COPYRIGHT: PostgreSQL Data Base Management System Portions
copyright (c) 1996-2002, PostgreSQL Global Development Group Portions
Copyright (c) 1994-6 Regents of the University of California
Permission to use, copy, modify, and distribute this software and its
documentation for any purpose, without fee, and without a written
agreement is hereby granted, provided that the above copyright notice
and this paragraph and the following two paragraphs appear in all
copies. IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO
ANY PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, INCLUDING LOST PROFITS, ARISING OUT OF THE USE OF THIS
SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA
HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. THE UNIVERSITY OF
CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS IS"
BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATIONS TO PROVIDE
MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS. The
above is the BSD license, the classic open-source license. It has no
restrictions on how the source code may be used. We like it and have
no intention of changing it. 1.3) What Unix platforms does PostgreSQL
run on? In general, a modern Unix-compatible platform should be able
to run PostgreSQL. The platforms that had received explicit testing at
the time of release are listed in the installation instructions. 1.4)
What non-Unix ports are available? *Client* It is possible to compile
the /libpq/ C library, psql, and other interfaces and client
applications to run on MS Windows platforms. In this case, the client
is running on MS Windows, and communicates via TCP/IP to a server
running on one of our supported Unix platforms. A file /win32.mak/ is
included in the distribution for making a Win32 /libpq/ library and
/psql/. PostgreSQL also communicates with ODBC clients. *Server* The
database server can run on Windows NT and Win2k using Cygwin, the
Cygnus Unix/NT porting library. See /pgsql/doc/FAQ_MSWIN/ in the
distribution or the MS Windows FAQ at
http://www.PostgreSQL.org/docs/faqs/text/FAQ_MSWIN
www.PostgreSQL.org/docs/faqs/text/FAQ_MSWIN>. A native port to MS Win
NT/2000/XP is currently being worked on. For more details on the
current status of PostgreSQL on Windows see
http://techdocs.postgresql.org/guides/Windows
techdocs.postgresql.org/guides/Windows>. There is also a Novell
Netware 6 port at http://forge.novell.com. 1.5) Where can I get
PostgreSQL? The primary anonymous ftp site for PostgreSQL is
ftp://ftp.PostgreSQL.org/pub. For mirror sites, see our main web site.
1.6) Where can I get support? The main mailing list is:
pgsql-general@PostgreSQL.org . It is available for discussion of
matters pertaining to PostgreSQL. To subscribe, send mail with the
following lines in the body (not the subject line): subscribe end to
pgsql-general-request@PostgreSQL.org . There is also a digest list
available. To subscribe to this list, send email to:
pgsql-general-digest-request@PostgreSQL.org with a body of: subscribe
end Digests are sent out to members of this list whenever the main
list has received around 30k of messages. The bugs mailing list is
available. To subscribe to this list, send email to
pgsql-bugs-request@PostgreSQL.org with a body of: subscribe end There
is also a developers discussion mailing list available. To subscribe
to this list, send email to pgsql-hackers-request@PostgreSQL.org with
a body of: subscribe end Additional mailing lists and information
about PostgreSQL can be found via the PostgreSQL WWW home page at:
http://www.PostgreSQL.org There is also an IRC channel on EFNet and
OpenProjects, channel /#PostgreSQL/. I use the Unix command |irc -c
'#PostgreSQL' "$USER" irc.phoenix.net.| A list of commercial support
companies is available at
http://www.ca.PostgreSQL.org/users-lounge/commercial-support.html.
1.7) What is the latest release? The latest release of PostgreSQL is
version 7.3.3. We plan to have major releases every four months. 1.8)
What documentation is available? Several manuals, manual pages, and
some small test examples are included in the distribution. See the
//doc/ directory. You can also browse the manuals online at
http://www.PostgreSQL.org/docs. There are two PostgreSQL books
available online at http://www.PostgreSQL.org/docs/awbook.html and
http://www.commandprompt.com/ppbook/. There is a list of PostgreSQL
books available for purchase at http://www.ca.PostgreSQL.org/books/.
There is also a collection of PostgreSQL technical articles at
http://techdocs.PostgreSQL.org/. /psql/ has some nice \d commands to
show information about types, operators, functions, aggregates, etc.
Our web site contains even more documentation. 1.9) How do I find out
about known bugs or missing features? PostgreSQL supports an extended
subset of SQL-92. See our TODO developer.PostgreSQL.org/todo.php> list
for known bugs, missing features, and future plans. 1.10) How can I
learn SQL? The PostgreSQL book at
http://www.PostgreSQL.org/docs/awbook.html teaches SQL. There is
another PostgreSQL book at http://www.commandprompt.com/ppbook.
www.commandprompt.com/ppbook/> There is a nice tutorial at
copies.
IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY
FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES,
INCLUDING LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND
ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN
ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE
PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE UNIVERSITY OF
CALIFORNIA HAS NO OBLIGATIONS TO PROVIDE MAINTENANCE, SUPPORT,
UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
stteki metin klasik ak-kod lisans olan BSD lisansdr. Kaynak kodun nasl
kullanlabileceine dair snrlamalar yoktur. Bu lisansi seviyoruz ve deitirme
niyetimiz bulunmamaktadr.
1.3) PostgreSQL, hangi Unix platforlarnda alsr?
Genel olarak, modern bir Unix-uyumlu platform PostgreSQL'i alstracaktr.
Ayrntl bilgi iin kurulum belgelerine bakabilirsiniz
1.4) Hangi Unix olmayan uyarlamalar bulunmaktadr?
stemci
libpq C ktphanesini, psql ve diger arabirimleri ve binary dosyalar, MS
Windows ortamlarnda alsmas iin derlemeniz mmkndr. Bu rnekte istemcide
MS Windows alsyor ve desteklenen Unix platformlarndan birinde alsan PostgreSQL
sunucuna TCP/IP ile baglanmaktadr. Datm iindeki win31.mak dosyas ile,
Win32 libpg ktphanesi ve psql yaratabilirsiniz. PostgreSQL ayn zamanda ODBC
istemcileri ile haberlesebilmektedir.
Sunucu
Veritaban sunuucsu Cygwin kullanarak Windows NT, 2K ya da XP zerinde calistirilabilir.
Dagtm iindeki pgsql/doc/FAQ_MSWN dosyasn ya da web sitemizdeki MS Windows FAQ'u
inceleyebilirsiniz.
Doal Windows NT/2000/XP portu iin u anda almalar devam etmektedir. Windows srm
hakknda gncel bilgi iin, http://techdocs.postgresql.org/guides/Windows adresini
ziyaret edebilirsiniz.
Ayrca, http://forge.novell.com adresinde Novell Netware 6 portu bulunmaktadr.
1.5) PostgreSQL'in nereden indirebilirim?
PostgreSQL iin ana anonim ftp sitesi ftp://ftp.PostgreSQL.org/pub ' dur.
Yanslar iin, ana web sayfamza bakabilirsiniz.
1.6) Destei nereden alabilirim?
Ana e-posta listesi : pgsql-general@PostgreSQL.org. PostgreSQL konusundaki tartsmalara
aktr. ye olmak iin, asagdaki satrlar e-postanizin body ksmna (konu ksmna degil)
yazp, pgsql-general-request@PostgreSQL.org adresine gnderin:
subscribe
end
Ayn zamanda, bir digest listesi bulunmaktadr. Bu listeye ye olmak iin,
pgsql-general-digest-request@PostgreSQL.org adresine, body ksmnda
subscribe
end
yazan bir e-posta atmanz yeterli olacaktr.
Digest postalar, ana liste 30k civarnda e-postaya ulastiginda yelere gnderilmektedir.
Buglar iin bir e-posta listesi bulunmaktadr. Bu listeye ye olmak iin,
email to pgsql-bugs-request@PostgreSQL.org adresine, body ksmnda
subscribe
end
yazan bir e-posta atmanz yeterli olacaktr.
Ayn zamanda, gelistiriciler iin tartsma listesi bulunmaktadr. Bu listeye ye olmak
iin, pgsql-hackers-request@PostgreSQL.org adresine, body ksmnda
subscribe
end
yazan bir e-posta atmanz yeterli olacaktr.
Bunun dsndaki e-posta listelerine ve PostgreSQL hakknda bilgiye, PostgreSQL WWW
ana sayfasndan ulasabilirsiniz:
http://www.PostgreSQL.org
Ayn zamanda, EFNet zerinde, #PostgreSQL adl bir RC kanal bulunmaktadr. Bunun iin,
irc -c '#PostgreSQL' "$USER" irc.phoenix.net Unix komutunu kullanabilirsiniz.
Ticari destek veren firmalarn listesine,
http://www.postgresql.org/users-lounge/commercial-support.html
adresinden ulasabilirsiniz.
1.7) En son srm nedir?
PostgreSQL'in son srm 7.3.3'tr.
Her 4 ayda major release karlmas planlanmaktadr.
1.8) Hangi belgelere ulasabilirim?
Datmn icinde, kitapciklar, kitapcik sayfalari ve bazi kk rnekler verilmektedir.
/doc dizinine baknz. Ayrica, bu el kitapklarn online olarak
http://www.PostgreSQL.org/docs/ adresinden inceleyebilirsiniz.
http://www.PostgreSQL.org/docs/awbook.html ve http://www.commandprompt.com/ppbook
adreslerinde PostgreSQL kitaplar bulunmaktadr. PostgreSQL kitablarnn listesine,
http://www.ca.PostgreSQL.org/books/ adresinden ulaaiblirsiniz. Ayrca, PostgreSQL
konusundaki teknik makalelere de http://techdocs.PostgreSQL.org/ adresinden
ulaabilirsiniz.
psql'in, \d ile baslayan veri tipler, operatorler, fonksiyonlar, aggregateler,vb. ile
ilgili gzel komutlar vardr.
Web sitemiz daha fazla belgeyi iermektedir.
1.9) Bilinen hatalar ya da eksik zelliklere nereden ulasabilirim?
PostgreSQL SQL-92 uyumlugugu icindedir, standartlardan fazla da zellikleri
bulunmaktadr. Bilinen hatalar, eksik zellikler ve gelecek ile ilgili planlar iin
TODO listesine baknz.
1.10) Nasl SQL grenebilirim?
http:/www.PostgreSQL.org/docs/awbook.html adresindeki kitap SQL gretecektir.
http://www.commandprompt.com/ppbook adresinde de bir baska PostgreSQL kitab bulunmaktadr.
http://www.intermedia.net/support/sql/sqltut.shtm,
www.intermedia.net/support/sql/sqltut.shtm> at
http://ourworld.compuserve.com/homepages/graeme_birchall/HTM_COOK.HTM,
ourworld.compuserve.com/homepages/graeme_birchall/HTM_COOK.HTM> and at
http://sqlcourse.com. sqlcourse.com/> Another one is "Teach Yourself
SQL in 21 Days, Second Edition" at
http://members.tripod.com/er4ebus/sql/index.htm Many of our users like
/The Practical SQL Handbook/, Bowman, Judith S., et al.,
Addison-Wesley. Others like /The Complete Reference SQL/, Groff et
al., McGraw-Hill. 1.11) Is PostgreSQL Y2K compliant? Yes, we easily
handle dates past the year 2000 AD, and before 2000 BC. 1.12) How do I
join the development team? First, download the latest source and read
the PostgreSQL Developers documentation on our web site, or in the
distribution. Second, subscribe to the /pgsql-hackers/ and
/pgsql-patches/ mailing lists. Third, submit high quality patches to
pgsql-patches. There are about a dozen people who have commit
privileges to the PostgreSQL CVS archive. They each have submitted so
many high-quality patches that it was impossible for the existing
committers to keep up, and we had confidence that patches they
committed were of high quality. 1.13) How do I submit a bug report?
Please visit the PostgreSQL BugTool page at
http://www.PostgreSQL.org/bugs/bugs.php, which gives guidelines and
directions on how to submit a bug report. Also check out our ftp site
ftp://ftp.PostgreSQL.org/pub to see if there is a more recent
PostgreSQL version or patches. 1.14) How does PostgreSQL compare to
other DBMSs? There are several ways of measuring software: features,
performance, reliability, support, and price. *Features* PostgreSQL
has most features present in large commercial DBMSs, like
transactions, subselects, triggers, views, foreign key referential
integrity, and sophisticated locking. We have some features they do
not have, like user-defined types, inheritance, rules, and
multi-version concurrency control to reduce lock contention.
*Performance* PostgreSQL has performance similar to other commercial
and open source databases. it is faster for some things, slower for
others. In comparison to MySQL or leaner database systems, we are
slower on inserts/updates because of transaction overhead. Of course,
MySQL does not have any of the features mentioned in the /Features/
section above. We are built for reliability and features, though we
continue to improve performance in every release. There is an
interesting Web page comparing PostgreSQL to MySQL at
http://openacs.org/philosophy/why-not-mysql.html
openacs.org/philosophy/why-not-mysql.html> *Reliability* We realize
that a DBMS must be reliable, or it is worthless. We strive to release
well-tested, stable code that has a minimum of bugs. Each release has
at least one month of beta testing, and our release history shows that
we can provide stable, solid releases that are ready for production
use. We believe we compare favorably to other database software in
this area. *Support* Our mailing lists provide contact with a large
group of developers and users to help resolve any problems
encountered. While we cannot guarantee a fix, commercial DBMSs do not
always supply a fix either. Direct access to developers, the user
community, manuals, and the source code often make PostgreSQL support
superior to other DBMSs. There is commercial per-incident support
available for those who need it. (See FAQ section 1.6 <#1.6>.) *Price*
We are free for all use, both commercial and non-commercial. You can
add our code to your product with no limitations, except those
outlined in our BSD-style license stated above. 1.15) How can I
financially assist PostgreSQL? PostgreSQL has had a first-class
infrastructure since we started in 1996. This is all thanks to Marc
Fournier, who has created and managed this infrastructure over the
years. Quality infrastructure is very important to an open-source
project. It prevents disruptions that can greatly delay forward
movement of the project. Of course, this infrastructure is not cheap.
There are a variety of monthly and one-time expenses that are required
to keep it going. If you or your company has money it can donate to
help fund this effort, please go to http://store.pgsql.com/shopping/
and make a donation. Although the web page mentions PostgreSQL, Inc,
the "contributions" item is solely to support the PostgreSQL project
and does not fund any specific company. If you prefer, you can also
send a check to the contact address.
----------------------------------------------------------------------
-- User Client Questions 2.1) Are there ODBC drivers for PostgreSQL?
There are two ODBC drivers available, PsqlODBC and OpenLink ODBC. You
can download PsqlODBC from
http://gborg.postgresql.org/project/psqlodbc/projdisplay.php
gborg.postgresql.org/project/psqlodbc/projdisplay.php>. OpenLink ODBC
can be gotten from http://www.openlinksw.com www.openlinksw.com/>. It
works with their standard ODBC client software so you'll have
PostgreSQL ODBC available on every client platform they support (Win,
Mac, Unix, VMS). They will probably be selling this product to people
who need commercial-quality support, but a freeware version will
always be available. Please send questions to
postgres95@openlink.co.uk . 2.2) What tools are available for using
PostgreSQL with Web pages? A nice introduction to Database-backed Web
pages can be seen at: http://www.webreview.com For Web integration,
PHP is an excellent interface. It is at http://www.php.net. For
complex cases, many use the Perl interface and CGI.pm or mod_perl.
2.3) Does PostgreSQL have a graphical user interface? Yes, there are
several graphical interfaces to PostgreSQL available. These include
PgAccess http://www.pgaccess.org www.pgaccess.org>), PgAdmin II
(http://www.pgadmin.org, Win32-only), RHDB Admin
(http://sources.redhat.com/rhdb/ ) and Rekall (
http://www.thekompany.com/products/rekall/
www.thekompany.com/products/rekall/>, proprietary). There is also
PHPPgAdmin ( http://phppgadmin.sourceforge.net/
phppgadmin.sourceforge.net/>), a web-based interface to PostgreSQL.
See http://techdocs.postgresql.org/guides/GUITools for a more detailed
list. 2.4) What languages are able to communicate with PostgreSQL?
Most popular programming languages contain an interface to PostgreSQL.
Check your programming language's list of extension modules. The
following interfaces are included in the PostgreSQL distribution: * C
(libpq) * Embedded C (ecpg) * Java (jdbc) * Python (PyGreSQL) * TCL
(libpgtcl) Additional interfaces are available at
http://gborg.postgresql.org in the /Drivers/Interfaces/ section.
----------------------------------------------------------------------
-- Administrative Questions 3.1) How do I install PostgreSQL somewhere
other than //usr/local/pgsql/? Specify the /--prefix/ option when
running /configure/. 3.2) When I start /postmaster/, I get a /Bad
System Call/ or core dumped message. Why? It could be a variety of
problems, but first check to see that you have System V extensions
installed in your kernel. PostgreSQL requires kernel support for
shared memory and semaphores. 3.3) When I try to start /postmaster/, I
get /IpcMemoryCreate/ errors. Why? You either do not have shared
memory configured properly in your kernel or you need to enlarge the
shared memory available in the kernel. The exact amount you need
depends on your architecture and how many buffers and backend
processes you configure for /postmaster/. For most systems, with
default numbers of buffers and processes, you need a minimum of ~1 MB.
See the PostgreSQL Administrator's Guide
www.PostgreSQL.org/docs/view.php?version=current&idoc=1&file=kernel-re
sources.html> for more detailed information about shared memory and
semaphores. 3.4) When I try to start /postmaster/, I get
/IpcSemaphoreCreate/ errors. Why? If the error message is
/IpcSemaphoreCreate: semget failed (No space left on device)/ then
your kernel is not configured with enough semaphores. Postgres needs
one semaphore per potential backend process. A temporary solution is
to start /postmaster/ with a smaller limit on the number of backend
processes. Use /-N/ with a parameter less than the default of 32. A
more permanent solution is to increase your kernel's SEMMNS and SEMMNI
parameters. Inoperative semaphores can also cause crashes during heavy
database access. If the error message is something else, you might not
have semaphore support configured in your kernel at all. See the
PostgreSQL Administrator's Guide for more detailed information about
shared memory and semaphores. 3.5) How do I control connections from
other hosts? By default, PostgreSQL only allows connections from the
local machine using Unix domain sockets. Other machines will not be
able to connect unless you add the /-i/ flag to /postmaster/, *and*
enable host-based authentication by modifying the file
/$PGDATA/pg_hba.conf/ accordingly. This will allow TCP/IP connections.
3.6) How do I tune the database engine for better performance?
Certainly, indexes can speed up queries. The EXPLAIN command allows
you to see how PostgreSQL is interpreting your query, and which
indexes are being used. If you are doing many INSERTs, consider doing
them in a large batch using the COPY command. This is much faster than
individual INSERTS. Second, statements not in a BEGIN WORK/COMMIT
transaction block are considered to be in their own transaction.
Consider performing several statements in a single transaction block.
This reduces the transaction overhead. Also, consider dropping and
recreating indexes when making large data changes. There are several
tuning options. You can disable /fsync()/ by starting /postmaster/
with a /-o -F/ option. This will prevent /fsync()/s from flushing to
disk after every transaction. You can also use the /postmaster/ /-B/
option to increase the number of shared memory buffers used by the
backend processes. If you make this parameter too high, the
/postmaster/ may not start because you have exceeded your kernel's
limit on shared memory space. Each buffer is 8K and the default is 64
buffers. You can also use the backend /-S/ option to increase the
maximum amount of memory used by the backend process for temporary
sorts. The /-S/ value is measured in kilobytes, and the default is 512
(i.e. 512K). You can also use the CLUSTER command to group data in
tables to match an index. See the CLUSTER manual page for more
details. 3.7) What debugging features are available? PostgreSQL has
several features that report status information that can be valuable
for debugging purposes. First, by running /configure/ with the
--enable-cassert option, many /assert()/s monitor the progress of the
backend and halt the program when something unexpected occurs. Both
/postmaster/ and /postgres/ have several debug options available.
First, whenever you start /postmaster/, make sure you send the
standard output and error to a log file, like: cd /usr/local/pgsql
./bin/postmaster >server.log 2>&1 & This will put a server.log file in
the top-level PostgreSQL directory. This file contains useful
information about problems or errors encountered by the server.
/Postmaster/ has a /-d/ option that allows even more detailed
information to be reported. The /-d/ option takes a number that
specifies the debug level. Be warned that high debug level values
generate large log files. If /postmaster/ is not running, you can
actually run the /postgres/ backend from the command line, and type
your SQL statement directly. This is recommended *only* for debugging
purposes. Note that a newline terminates the query, not a semicolon.
If you have compiled with debugging symbols, you can use a debugger to
see what is happening. Because the backend was not started from
/postmaster/, it is not running in an identical environment and
locking/backend interaction problems may not be duplicated. If
/postmaster/ is running, start /psql/ in one window, then find the PID
of the /postgres/ process used by /psql/. Use a debugger to attach to
the /postgres/ PID. You can set breakpoints in the debugger and issue
queries from /psql/. If you are debugging /postgres/ startup, you can
set PGOPTIONS="-W n", then start /psql/. This will cause startup to
delay for /n/ seconds so you can attach to the process with the
debugger, set any breakpoints, and continue through the startup
sequence. The /postgres/ program has /-s, -A/, and /-t/ options that
can be very useful for debugging and performance measurements. You can
also compile with profiling to see what functions are taking execution
time. The backend profile files will be deposited in the
/pgsql/data/base/dbname/ directory. The client profile file will be
put in the client's current directory. Linux requires a compile with
/-DLINUX_PROFILE/ for proper profiling. 3.8) Why do I get /"Sorry, too
many clients"/ when trying to connect? You need to increase
/postmaster/'s limit on how many concurrent backend processes it can
start. The default limit is 32 processes. You can increase it by
restarting /postmaster/ with a suitable /-N/ value or modifying
/postgresql.conf/. Note that if you make /-N/ larger than 32, you must
also increase /-B/ beyond its default of 64; /-B/ must be at least
twice /-N/, and probably should be more than that for best
performance. For large numbers of backend processes, you are also
likely to find that you need to increase various Unix kernel
configuration parameters. Things to check include the maximum size of
shared memory blocks, SHMMAX; the maximum number of semaphores, SEMMNS
and SEMMNI; the maximum number of processes, NPROC; the maximum number
of processes per user, MAXUPRC; and the maximum number of open files,
NFILE and NINODE. The reason that PostgreSQL has a limit on the number
of allowed backend processes is so your system won't run out of
resources. 3.9) What is in the /pgsql_tmp/ directory? This directory
contains temporary files generated by the query executor. For example,
if a sort needs to be done to satisfy an ORDER BY and the sort
requires more space than the backend's /-S/ parameter allows, then
temporary files are created here to hold the extra data. The temporary
files are usually deleted automatically, but might remain if a backend
crashes during a sort. A stop and restart of the /postmaster/ will
remove files from those directories. 3.10) Why do I need to do a dump
and restore to upgrade between major PostgreSQL releases? The
PostgreSQL team makes only small changes between minor releases, so
upgrading from 7.2 to 7.2.1 does not require a dump and restore.
However, major releases (e.g. from 7.2 to 7.3) often change the
internal format of system tables and data files. These changes are
often complex, so we don't maintain backward compatability for data
files. A dump outputs data in a generic format that can then be loaded
in using the new internal format. In releases where the on-disk format
does not change, the /pg_upgrade/ script can be used to upgrade
without a dump/restore. The release notes mention whether /pg_upgrade/
is available for the release.
----------------------------------------------------------------------
-- Operational Questions 4.1) What is the difference between binary
cursors and normal cursors? See the DECLARE manual page for a
description. 4.2) How do I SELECT only the first few rows of a query?
See the FETCH manual page, or use SELECT ... LIMIT.... The entire
query may have to be evaluated, even if you only want the first few
rows. Consider using a query that has an ORDER BY. If there is an
http://ourworld.compuserve.com/homepages/graeme_birchall/HTM_COOK.HTM
http://sqlcourse.com ve http://sqlcourse2.com adreslerinde de gzel belgeler bulunmaktadr.
Bir bakas da, http://members.tripod.com/er4ebus/sql/index.htm adresinde bulunan
"Teach Yourself SQL in 21 Days, Second Edition" kitabdr.
Baz kullanclarmz da u kitab nermektedirler:
The Practical SQL Handbook, Bowman, Judith S., et al.,Addison-Wesley. Others
like The Complete Reference SQL, Groff et al., McGraw-Hill.
1.11) PostgreSQL 2000 ylna uyumlu mudur?
Evet.
1.12) Gelistirme takmna nasl katlabilirim?
ncelikle, en son kaynak kodunu indirin ve web sitemizdeki ya da dagtmn iindeki
PostgreSQL Developer belgesini okuyun. Ardindan, pgsql-hackers ve pgsql-patches
listelerine ye olun. nc olarak da, pgsql-pacthes listesine yksek kalitede
yamalar gnderin.
PostgreSQL CVS arsivine erisim izni olan, 10 kadar gelistirici bulunmaktadir.
Hepsi defalarca, diger kisilerin yaptigindan cok daha yksek-kaliteli patchler
gondermislerdir. Ayrica biz de bu gelistiricilerin ekledikleri yamalarin yksek
kalitede olduguna gveniyoruz.
1.13) Bir hata raporunu nasl gnderebilirim?
PostgreSQL BugTool sayfasina gidiniz. O sayfada bir bug bildirmek icin neleri
yapmanz gerektigi anlatilmistir.
Ayrca, ftp://ftp.PostgreSQL.org/pub ftp adresimizde, yeni bir PostgreSQL srm
ya da yamasi olup olmadigini kontrol ediniz.
1.14) PostgreSQL, diger DBMS'lerle nasl karsilastrlabilir?
Bir yazilimin gcn lmek iin esitli yollar vardir: Yazilimin zellikleri,
basarm, gvenilirligi, destegi ve creti.
zellikler
PostgreSQL mevcut byk ticari veritabanlarinin, transaction, subselect,
trigger, view, foreign key referential integrity ve sophisticated locking gibi
tm zelliklerine sahiptir. Onlarin sahip olmadiklari, kullanici-tanimli tipler
(user-defined types), rules, inheritance ve lock caksmalarini dsrmek icin
multi-version uyumluluk zellikleri bulunmaktadir.
Performans (Baarm)
PostgreSQL, dier ticari ve ak kaynak kodlu veritabanlaryla yakn baarm salar.
Baz alardan daha hzldr, dier alardan da yavatr. MySQL ya da daha zayf
veritabanlar ile karlatrldnda,insert/update islemlerinde, transaction bazl
alstmz iin daha yavaz. MySQL, yukardaki "zellikler" ksmnda belirtilenlerden
hi birine sahip deildir. Biz, baarmmz her srmde arttrsak da, esneklik ve
gelimi zellikler iin yaplanms durumdayz . PostgreSQL'i MySQL ile karlatran
u web sitesine bakabilirsiniz: http://openacs.org/why-not-mysql.html
Gvenilirlik
DBMSlerin gvenilir olmas gerketigi, yoksa degerleri olmayacagini dsnyoruz
ok iyi test edilmis, dengeli alsan minimum sayda hata ieren kod sunmaya alsyoruz.
Her bir srm en az 1 aylk beta testlerinden geirilmektedir. Srm gemiine bakarsanz,
retime hazr, dengeli ve kararl kodlar sundugumuzu grebilirsiniz. Bu alanda, diger
veritaban yaZlmlarna stnlgmz olduguna inanmaktayz
Destek
E-posta listemiz, olusan herhangi bir sorunu zebilecek byk sayda kullanc
ve gelistirici grubunu ierir. Sorununuz iin, en az bir ticari veritaban kadar
rahat zm bulabilirsiniz. Gelistiricilere, kullanc grubuna, belgelere ve
kaynak koda direk olarak erisebilme, PostgreSQL destegini, diger DBMSlere gre daha
nemli klar. Gereksinimi olanlara, ticari destek verilebilir. (Destek iin 1.6 blmne baknz.)
Fiyat
Ticari ve ticari olmayan tm kullanmlarnz iin PostgreSQL cretsizdir. Kodumuzu, yukarda belirtilen
BSD-stili lisanstaki snrlamalar hari, rnnzn iine ekleyebilirsiniz.
1.15) PostgreSQL'e maddi adan nasl destek olabilirim?
PostgreSQL, 1996 ylndan beri 1.snf altyapya ashiptir. Bunun iin, yllar boyu alsp bu altyapy
olusturup yneten Marc Fournier'e tesekkrler.
Bir ak kaynak kodlu proje iin, kaliteli altyap ok nemlidir. Bu altyap, projenin
kesilmesini nler ve projenin ilerlemesini hzlandrr.
Tabii ki bu altyap ucuz degildir. slerin yrmesi iin eitli ylk ve anlk
harcamalarmz olmaktadr. Eger siz ya da sirketinizin bu abamza bagsta
bulunabilecek paras varsa, ltfen http://www.pgsql.com/pg_goodies adresine
gidiniz ve bagsta, hibede bulununuz.
Web sayfasnn PostgreSQL, nc.' den bahsetmesine ragmen, "katkda bulunanlar"
(contributors) maddesi sadece PostgreSQL projesini desteklemek iindir ve belirli bir
sirketin para kaynag degildir. isterseniz, baglant adresine bir ek gnderebilirsiniz.
____________________________________________________________________________
Kullanc/istemci Sorular
2.1) PostgreSQL icin ODBC srcleri var m?
iki tane ODBC srcs bulunmaktadr: PsqlODBC ve OpenLink ODBC.
PsqlODBC'i http://gborg.postgresql.org/project/psqlodbc/projdisplay.php adresinden
indirebilirsiniz.
OpenLink ODBC http://www.openlinksw.com adresinden alnabilir.Bu src,
kendi standart ODBC istemci yazlm ile alstndan, destekledikleri
her platformda (Win, Mac, Unix, VMS) PostgreSQL ODBC bulunmalidir.
cretsiz srm olmakla beraber, ticari kalitede destek almak isteyenlere satmak isteyeceklerdir.
Sorularnz ltfen postgres95@openlink.co.uk adresine gnderiniz.
2.2) PostgreSQL'i web sayfalarnda kullanabilmek iin hangi aralar bulunmaktadr?
http://www.webreview.com adresinde, arka planda veritaban alstran Web sayfalar
iin giris seviyesinde bilgi bulunmaktadr.
Web ile btnlesme iin, PHP mkemmel bir arabirim sunar. http://www.php.net .
Karmak sorunlar iin, ou kisi Perl arabirimini ve CGI.pm ya da mod_perl kullanr.
2.3) PostgreSQL'in grafik kullanc arabirimi var mdr?
eitli grafik arabirimlerimiz bulunmaktadr. Bunlarn arasnda, PgAccess (http://www.pgaccess.org),
PgAdmin II (http://www.pgadmin.org, sadece Win32 iin), RHDB Admin (http://sources.redhat.com/rhdb/ )
ve Rekall (http://www.thekompany.com/products/rekall/) bulunmaktadr. Ayrca, PostgreSQL iin web
tabanl bir arabirim olan PHPPgAdmin ( http://phppgadmin.sourceforge.net/ ) bulunmaktadr.
Daha ayrntl liste iin http://techdocs.postgresql.org/guides/GUITools adresine bakabilirsiniz.
2.4) PostgreSQL ile iletiimi kurabilmek iin hangi dilleri kullanabilirim?
* C (libpq)
* Embedded C (ecpg)
* Java (jdbc)
* Python (PyGreSQL)
* TCL (libpgtcl)
Dierleri iin, http://gborg.postgresql.org adresindeki Drivers/Interfaces blmne
bakabilirsiniz.
_________________________________________________________________
Ynetimsel Sorular
3.1) PostgreSQL'i, /usr/local/pgsql dizininden baska dizinlere nasl kurabilirim?
configure betigini alstrrken, --prefix seenegini veriniz.
3.2) postmaster'i baslattgmda, a Bad System Call ya da core dumped mesaj
alyorum. Neden?
Bunun birok nedeni olabilir. Ancak ilk kontrol edilmesi gereken sey, ekirdeginize
System V uzantlarnn kurulu olup olmadgn kontrol etmek olabilir. PostgreSQL
shared memory ve semaphores iin ekirdek destegine gereksinim duyar.
3.3) postmaster'i baslattgmda, a pcMemoryCreate hatas alyorum. Neden?
Ya ekirdeginizde shared memory desteginiz dzgnce yaplandrlmamstr, ya da
ekirdeginizdeki mevcut shared memory miktarn bytmeniz gerekecektir. Gereksinim
duyacagnz miktar, mimarinize ve postmaster iin ayarladgnz tampon ile backend
islemi saysna bagldr. Tm sistemler iin, tamponlar ve islemlerde ntanml saylarla,
~ 1MB kadar yere gereksinmeniz olacaktir.PostgreSQL Administrator's Guide' a, shared memory
ve semaphorelar hakkndaki ayrntl bilgi iin bakabilirsiniz.
3.4) postmaster'i baslattgmda, a pcSemaphoreCreate hatas alyorum. Neden?
Eger hata, "pcSemaphoreCreate: semget failed (No space left on device)" ise,
ekirdeginiz yeterli semaphore ile yaplandrlmams demektir. Postgres, her
bir potansiyel backend iin bir semaphore gereksinmesi duyar. Geici bir zm,
postmaster backend islemleri iin daha az miktarda snrla baslatmak olabilir.
-N i varsalan deger olan 32'den kk bir degerle baslatnz. Daha kalc bir
zm, ekirdeinizin SEMMNS ve SEMMNI parametrelerini ykseltmek olacaktr.
almayan semaphorelar ar veritaban islemlerinde kme yaratabilirler.
Eger hata mesajnz baska birsey ise, ekirdeginizde semaphore destegini
yaplandrmams olabilirsiniz. Shared memory ve semaphorelar hakkndaki daha
ayrntl bilgi iin PostgreSQL Administrator's Guide'a bakabilirsiniz.
3.5) Diger bilgisayarlarn benim PostgreSQL veritaban sunucuma baglantlarn
nasl kontrol edebilirim?
n tanml olarak, PostgreSQL sadece yerel makineden Unix domain sockets kullanarak
baglanlmasna izin verir. Diger makineler, postmaster'a -i etiketini geirmezseniz
ve $PGDATA_pg_hba.conf dosyasn dzenleyerek host-based authentication'a
olanak vermezseniz, baglant yapamayacaklardr.
3.6) Veritabani motorunu daha iyi basarim icin nasil ayarlayabilirim?
Indexler sorgular hzlandrabilir. EXPLAIN komutu, PostgreSQL'in sorgunuzu nasl
yorumladn ve hangi indexleri kullandigini grmenize izin verir.
Eer cok fazla INSERT islemi yapiyorsaniz, bunlar byk bir toplu islem dosyasi kullanp
COPY komutu ile veritabanina girmeyi deneyiniz. Bu, tekil NSERTlerden daha hzldr.
ikinci olarak, BEGN WORK/COMMT transaction blogu iinde olmayan ifadeler kendi
transactionlarindaymis gibi dsnlr. oklu ifadeleri tek bir transaction blou iinde
yapabilirsiniz. Bu, transaction overheadini drecektir. Tek bir
transaction blou iinde birden ok ifadeyi altrmay
deneyebilirsiniz. Bu, transaction overhead ini drr.
eitli ayarlama seenekleri mevcuttur. fsync() ilemini, postmaster' -o -F seenei ile
balatarak devre d brakabilirsiniz. Bu ilem, fsync()'lerin her transactiondan sonra
diske flush etmesini engelleyecektir.
Ayn zamanda, postmaster'i -B seenei ile balatp, backend ilemleri tarafndan kullanlan
shared memorf buffers saylarn arttrabilirsiniz. Eger bu parametreyi ok yksek tutarsanz,
ekirdeinizin shared memory blgesindeki limiti ama olaslnz yznden postmaster
balayamayabilir. Her bir tampon (buffer) 8K'dr. ntanml say ise 64 tampondur.
Ayn ekilde, backend'in -S seeneini geici sralamalar iin backend sreleri tarafndan
kullanlacak hafzay arttrmak amacyla kullanabilirsiniz. -S seenei kilobayt cinsinden deer alr
ve n tanml deeri 512'dir (512 K)
Tablolardaki veriyi bir indekse elemek amacyla gruplama iin CLUSTER komutunu kullanabilirsiniz.
Ayrntl bilgi iin CLUSTER komutunun yardm sayfasna bakabilirsiniz.
3.7) Hangi hata ayklama zellikleri bulunmaktadr?
PostgreSQL, hata ayklama amacyla kullanlabilecek durum bilgisi rapor eden eitli
zeliklere sahiptir.
ncelikle, configure betiini --enable-cassert seeneiyle altrrsanz, bir ok assert() backend calmasn
gzlemler ve beklenmeyen bir durumda program durdurur.
Postmaster ve postgres eitli hata ayklama seeneklerine sahiptir. ncelikle,
postmaster'i balattnzda, standart kty ve hatalar bir log dosyasna
ynlendirdiinize emin olun:
cd /usr/local/pgsql
./bin/postmaster >server.log 2>&1 &
Bu ilem PostgreSQL ana dizinine server.log dosyas yerletirecektir. Bu dosya sunucunun
yaad sorunlar ya da hatalar hakknda yararl bilgiler ierir. -d seenei, hata
ayklama seviyesini belirten bir rakam ile kullanlr. Yksek hata ayklama
seviyelerinin byk log dosyalar oluturacan unutmaynz.
Eer postmaster almyorsa, postgres backend'ini komut satrndan altrabilir ve SQL ifadenizi
direk olarak yazabilirsiniz. Bu sadece hata ayklama amacyla nerilir. Burada, noktal virgln deil de
yeni bir satrn sorguyu sonlandrdn unutmaynz. Eer hata ayklama sembolleri ile derlediyseniz,
ne olduunu grmek iin bir hata ayklayc kullanabilirsiniz. backend postmasterdan balatlmadndan,
edeer bir ortamda almamaktadr ve locking/backend etkileim sorunlar artabilir.
Eer postmaster alyorsa, bir pencerede psql'i altrn ve psql tarafndan kullanlan postgres srecinin sre
numarasn (PID) bulun. Postgres sreci ile ilikilendirmek iin bir hata ayklarc kullann. Sorgular psql
aracl ile altrabilirsiniz. Eer postgres balangcnda hata ayklamak istiyorsanz, PGOPTIONS="-W n"
seeneini ayarlayabilir ve psql'i balatabilirsiniz. Bu ilem, balangcn n saniye kadar gecikmesini
salayacaktr; bylece hata ayklaycy srece ilikilendirdikten sonra balang srecinin devam etmesini
salayabilirsiniz.
postgres program hata ayklama ve baarm lmleri iin -s, -A ve -t seeneklerine sahiptir.
3.8) Baglanmaya alsken, neden "Sorry, too many clients" hatasn alyorum?
Postmaster'in ezamanl olarak balatabilecei backend sreleri snrlarn
arttrmanz gerekmektedir.
n tanml deer 32 sretir. Bunu, postmaster'i uygun -N deeri ile ya da
postgresql.conf dosyasn dzenleyerek yeniden balatmakla arttrabilirsiniz.
Eer -N deerini 32'den byk yapacaksanz, ayn zamanda -B deerini de deitirmeniz
gerektiini unutmayn. -B -N'nin en az 2 kat kadar olmaldr; daha iyi baarm iin
bu sayy daha da arttrmalsnz. Yksek saydaki backend sreleri iin, eitli ekirdek yaplandrma
parametrelerini arttrmanz gerekecektir. Yaplmas gerekenler, SHMMAX, SEMMNS, SEMMNI, NPROC, MAXUPRC ve
alabilecek dosyalarn maksimum says olan NFILE ve NINODE deerlerini kartrmaktr. Bunun nedeni, PostgreSQL'in
izin verilen backend srelerinin says zerinde bir snr olmasdr. Bylelikle sistem kaynaklarnn dna
klmayacaktr.
PostgreSQL'in 6.5 srmne kadar, en fazla backend says 64 idi ve bunu deitirmek iin
include/storage/sinvaladt.h dosyas iindeki MaxBAckendid sabitini deitirdek sonra
yazlm yeniden derlemek gerekiyordu.
3.9) pgsql_tmp dizinin iindeki dosyalar nelerdir?
Sorgu alstrc (query executer) tarafndan yaratlan geici dosyalardr. rnegin,
bir sralama ORDER BY ile yapilacaksa ve sralama backend'in -s parametresinin izin
verdiginden daha fazla alana gereksinim duyuyorsa, ekstra veriyi tutmak iin geici
dosyalar yaratlr.
Geici dosyalar, eger sralama srasnda backend gmezse otomatik olarak silinecektir.
Eger alsan durumda bir backendiniz yoksa, pg_tempNNN.NN dosyalarn silmeniz gvenlidir..
3.10) PostgreSQL srmlerini ykselmek iin neden bir dump/reload ilemi gerekletirmek zorundaym?
PostgreSQL takm ara srmlerde sadece kk deiiklikler yapmaktadr; bu yzden 7.2
srmnden 7.2.1'e ykseltmek dump/restore ilemi gerekmemektedir. Ancak, esas srmlerde
(rnek: 7.2'den 7.3'e) ounlukla sistem tablolarnn ve veri dosyalarnn i yaps
deitirilir. Bu deiiklikler ounlukla karmaktr; dolaysyla veri dosyalarnn
geriye dnk uyumluluu ilemlerini yapmyoruz. Dump ilemi, veriyi genel biimde
alacandan yeniden ykleme esnasnda veri, yeni i biime uygun ekilde
yerletirilecektir.
Disk biiminin deimedii srmlerde, pg_upgrade betii gncellemenin bir dump/restore
gerektirmeden yaplmasn salayacaktr. pg_upgrade betiinin o srm iin bulunup
bulunmadn srm notlar iinde bulabilirsiniz.
_________________________________________________________________
letimsel Sorular
4.1) Binary cursor ve normal cursor arasindaki fark nedir?
DECLARE yardm sayfasina bakiniz.
4.2) Sorgunun sadece ilk birka satrn nasil SELECT edebilirim?
FETCH yardm sayfasina bakiniz, aya da SELECT ... LIMIT.... kullannz.
The entire query may have to be evaluated, even if you only want the
first few rows. Consider a query that has an ORDER BY. f there is an
index that matches the ORDER BY, PostgreSQL may be able to evaluate
only the first few records requested, or the entire query may have to
be evaluated until the desired rows have been generated. 4.3) How do I
get a list of tables or other things I can see in /psql/? You can read
the source code for /psql/ in file /pgsql/src/bin/psql/describe.c/. It
contains SQL commands that generate the output for psql's backslash
commands. You can also start /psql/ with the /-E/ option so it will
print out the queries it uses to execute the commands you give. 4.4)
How do you remove a column from a table? This functionality was added
in release 7.3 with ALTER TABLE DROP COLUMN. In earlier versions, you
can do this: BEGIN; LOCK TABLE old_table; SELECT ... -- select all
columns but the one you want to remove INTO TABLE new_table FROM
old_table; DROP TABLE old_table; ALTER TABLE new_table RENAME TO
old_table; COMMIT; 4.5) What is the maximum size for a row, a table,
and a database? These are the limits: Maximum size for a database?
unlimited (4 TB databases exist) Maximum size for a table? 16 TB
Maximum size for a row? 1.6TB Maximum size for a field? 1 GB Maximum
number of rows in a table? unlimited Maximum number of columns in a
table? 250-1600 depending on column types Maximum number of indexes on
a table? unlimited Of course, these are not actually unlimited, but
limited to available disk space and memory/swap space. Performance may
suffer when these values get unusually large. The maximum table size
of 16 TB does not require large file support from the operating
system. Large tables are stored as multiple 1 GB files so file system
size limits are not important. The maximum table size and maximum
number of columns can be increased if the default block size is
increased to 32k. 4.6) How much database disk space is required to
store data from a typical text file? A PostgreSQL database may require
up to five times the disk space to store data from a text file. As an
example, consider a file of 100,000 lines with an integer and text
description on each line. Suppose the text string avergages twenty
bytes in length. The flat file would be 2.8 MB. The size of the
PostgreSQL database file containing this data can be estimated as 6.4
MB: 36 bytes: each row header (approximate) 24 bytes: one int field
and one text field + 4 bytes: pointer on page to tuple
---------------------------------------- 64 bytes per row The data
page size in PostgreSQL is 8192 bytes (8 KB), so: 8192 bytes per page
------------------- = 128 rows per database page (rounded down) 64
bytes per row 100000 data rows -------------------- = 782 database
pages (rounded up) 128 rows per page 782 database pages * 8192 bytes
per page = 6,406,144 bytes (6.4 MB) Indexes do not require as much
overhead, but do contain the data that is being indexed, so they can
be large also. NULLs are stored in bitmaps, so they use very little
space. 4.7) How do I find out what tables, indexes, databases, and
users are defined? /psql/ has a variety of backslash commands to show
such information. Use \? to see them. There are also system tables
beginning with /pg_/ that describe these too. Also, /psql -l/ will
list all databases. Also try the file
/pgsql/src/tutorial/syscat.source/. It illustrates many of the SELECTs
needed to get information from the database system tables. 4.8) My
queries are slow or don't make use of the indexes. Why? Indexes are
not automatically used by every query. Indexes are only used if the
table is larger than a minimum size, and the query selects only a
small percentage of the rows in the table. This is because the random
disk access caused by an index scan can be slower than a straight read
through the table, or sequential scan. To determine if an index should
be used, PostgreSQL must have statistics about the table. These
statistics are collected using VACUUM ANALYZE, or simply ANALYZE.
Using statistics, the optimizer knows how many rows are in the table,
and can better determine if indexes should be used. Statistics are
also valuable in determining optimal join order and join methods.
Statistics collection should be performed periodically as the contents
of the table change. Indexes are normally not used for ORDER BY or to
perform joins. A sequential scan followed by an explicit sort is
usually faster than an index scan of a large table. However, LIMIT
combined with ORDER BY often will use an index because only a small
portion of the table is returned. In fact, though MAX() and MIN()
don't use indexes, it is possible to retrieve such values using an
index with ORDER BY and LIMIT: SELECT col FROM tab ORDER BY col [ DESC
] LIMIT 1; If you believe the optimizer is incorrect in choosing a
sequential scan, use |SET enable_seqscan TO 'off'| and run tests to
see if an index scan is indeed faster. When using wild-card operators
such as LIKE or /~/, indexes can only be used in certain
circumstances: * The beginning of the search string must be anchored
to the start of the string, i.e. o LIKE patterns must not start with
/%/. o /~/ (regular expression) patterns must start with /^/. * The
search string can not start with a character class, e.g. [a-e]. *
Case-insensitive searches such as ILIKE and /~*/ do not utilise
indexes. Instead, use functional indexes, which are described in
section 4.12 <#4.12>. * The default /C/ locale must be used during
/initdb/. 4.9) How do I see how the query optimizer is evaluating my
query? See the EXPLAIN manual page. 4.10) What is an R-tree index? An
R-tree index is used for indexing spatial data. A hash index can't
handle range searches. A B-tree index only handles range searches in a
single dimension. R-trees can handle multi-dimensional data. For
example, if an R-tree index can be built on an attribute of type
/point/, the system can more efficiently answer queries such as
"select all points within a bounding rectangle." The canonical paper
that describes the original R-tree design is: Guttman, A. "R-trees: A
Dynamic Index Structure for Spatial Searching." Proceedings of the
1984 ACM SIGMOD Int'l Conf on Mgmt of Data, 45-57. You can also find
this paper in Stonebraker's "Readings in Database Systems". Built-in
R-trees can handle polygons and boxes. In theory, R-trees can be
extended to handle higher number of dimensions. In practice, extending
R-trees requires a bit of work and we don't currently have any
documentation on how to do it. 4.11) What is the Genetic Query
Optimizer? The GEQO module speeds query optimization when joining many
tables by means of a Genetic Algorithm (GA). It allows the handling of
large join queries through nonexhaustive search. 4.12) How do I
perform regular expression searches and case-insensitive regular
expression searches? How do I use an index for case-insensitive
searches? The /~/ operator does regular expression matching, and /~*/
does case-insensitive regular expression matching. The
case-insensitive variant of LIKE is called ILIKE. Case-insensitive
equality comparisons are normally expressed as: SELECT * FROM tab
WHERE lower(col) = 'abc'; This will not use an standard index.
However, if you create a functional index, it will be used: CREATE
INDEX tabindex ON tab (lower(col)); 4.13) In a query, how do I detect
if a field is NULL? You test the column with IS NULL and IS NOT NULL.
4.14) What is the difference between the various character types? Type
Internal Name Notes --------------------------------------------------
VARCHAR(n) varchar size specifies maximum length, no padding CHAR(n)
bpchar blank padded to the specified fixed length TEXT text no
specific upper limit on length BYTEA bytea variable-length byte array
(null-byte safe) "char" char one character You will see the internal
name when examining system catalogs and in some error messages. The
first four types above are "varlena" types (i.e., the first four bytes
on disk are the length, followed by the data). Thus the actual space
used is slightly greater than the declared size. However, these data
types are also subject to compression or being stored out-of-line by
TOAST, so the space on disk might also be less than expected.
VARCHAR(n) is best when storing variable-length strings and it limits
how long a string can be. TEXT is for strings of unlimited length,
with a maximum of one gigabyte. CHAR(n) is for storing strings that
are all the same length. CHAR(n) pads with blanks to the specified
length, while VARCHAR(n) only stores the characters supplied. BYTEA is
for storing binary data, particularly values that include NULL bytes.
All the types described here have similar performance characteristics.
4.15.1) How do I create a serial/auto-incrementing field? PostgreSQL
supports a SERIAL data type. It auto-creates a sequence and index on
the column. For example, this: CREATE TABLE person ( id SERIAL, name
TEXT ); is automatically translated into this: CREATE SEQUENCE
person_id_seq; CREATE TABLE person ( id INT4 NOT NULL DEFAULT
nextval('person_id_seq'), name TEXT ); CREATE UNIQUE INDEX
person_id_key ON person ( id ); See the /create_sequence/ manual page
for more information about sequences. You can also use each row's
/OID/ field as a unique value. However, if you need to dump and reload
the database, you need to use /pg_dump/'s /-o/ option or COPY WITH
OIDS option to preserve the OIDs. 4.15.2) How do I get the value of a
SERIAL insert? One approach is to retrieve the next SERIAL value from
the sequence object with the /nextval()/ function /before/ inserting
and then insert it explicitly. Using the example table in 4.15.1
<#4.15.1>, an example in a pseudo-language would look like this:
new_id = execute("SELECT nextval('person_id_seq')"); execute("INSERT
INTO person (id, name) VALUES (new_id, 'Blaise Pascal')"); You would
then also have the new value stored in |new_id| for use in other
queries (e.g., as a foreign key to the |person| table). Note that the
name of the automatically created SEQUENCE object will be named
__/seq/, where /table/ and /serialcolumn/ are the names of your table
and your SERIAL column, respectively. Alternatively, you could
retrieve the assigned SERIAL value with the /currval()/ function
/after/ it was inserted by default, e.g., execute("INSERT INTO person
(name) VALUES ('Blaise Pascal')"); new_id = execute("SELECT
currval('person_id_seq')"); Finally, you could use the OID <#4.16>
returned from the INSERT statement to look up the default value,
though this is probably the least portable approach. In Perl, using
DBI with Edmund Mergl's DBD::Pg module, the oid value is made
available via /$sth->{pg_oid_status}/ after /$sth->execute()/. 4.15.3)
Don't /currval()/ and /nextval()/ lead to a race condition with other
users? No. /currval()/ returns the current value assigned by your
backend, not by all users. 4.15.4) Why aren't my sequence numbers
reused on transaction abort? Why are there gaps in the numbering of my
sequence/SERIAL column? To improve concurrency, sequence values are
given out to running transactions as needed and are not locked until
the transaction completes. This causes gaps in numbering from aborted
transactions. 4.16) What is an OID? What is a TID? OIDs are
PostgreSQL's answer to unique row ids. Every row that is created in
PostgreSQL gets a unique OID. All OIDs generated during /initdb/ are
less than 16384 (from /include/access/transam.h/). All user-created
OIDs are equal to or greater than this. By default, all these OIDs are
unique not only within a table or database, but unique within the
entire PostgreSQL installation. PostgreSQL uses OIDs in its internal
system tables to link rows between tables. These OIDs can be used to
identify specific user rows and used in joins. It is recommended you
use column type OID to store OID values. You can create an index on
the OID field for faster access. OIDs are assigned to all new rows
from a central area that is used by all databases. If you want to
change the OID to something else, or if you want to make a copy of the
table, with the original OIDs, there is no reason you can't do it:
CREATE TABLE new_table(old_oid oid, mycol int); SELECT old_oid, mycol
INTO new FROM old; COPY new TO '/tmp/pgtable'; DELETE FROM new; COPY
new WITH OIDS FROM '/tmp/pgtable'; OIDs are stored as 4-byte integers,
and will overflow at 4 billion. No one has reported this ever
happening, and we plan to have the limit removed before anyone does.
be evaluated until the desired rows have been generated.
4.3) psql'in iinde grdgm tablolarin ya da diger seylerin listesini nasil alabilirim?
pgsql/src/bin/psql/describe.c iindeki psql kaynak kodunu okuyabilirsiniz. Bu kod,
psql'in \ ile baslayan komutlarnn ktsn olusturan SQL komutlarini ierir. Ayn
zamanda, psql'i -E seenei ile balatp, verdiiniz komutlar altrmak iin yapt
sorgularn ktlarn grebilirsiniz.
4.4) Bir tablodan bir kolonu nasl kaldrabilirim?
Bu zellik (ALTER TABLE DROP COLUMN) 7.3 srm ile gelmitir. Eski srmlerde
aadakileri uygulamalsnz:
BEGIN;
LOCK TABLE old_table;
SELECT ... -- select all columns but the one you want to remove
INTO TABLE new_table
FROM old_table;
DROP TABLE old_table;
ALTER TABLE new_table RENAME TO old_table;
COMMIT;
4.5) Bir satr, tablo ve veritaban icin en fazla byklk nedir?
Snrlar:
Veritabani icin en fazla byklk nedir? Snrsz (4 TB'lk veritaban bulunmaktadr)
Bir tablo icin en fazla byklk nedir? 16 TB
Bir satr iin en fazla byklk nedir? 1.6 TB
Bir alan iin en fazla byklk nedir? 1 GB
Tabloda en fazla satr says katr? Snrsz
Bir tabloda olabilecek en fazla kolon says katr? Kolon tiplerine bal olarak 250-1600
Bir tabloda olabilecek en fazla index says katr? snrsz
Tabii ki bunlar aslinda snrsz degildir. Burada belirtilen snrlar, fiziksel
snrlarn haricindeki snrlardr. Bo disk alan, hafza/takas alan na bal
snrlamalar vardr. Baarm, snr deerlere yaklastka, ya da deerler cok byk
olduunda debilir.
Bir tablo iin byklk snr olan 16 TB, iletim sisteminin byk dosya destei olup
olmamasndan bamszdr. Byk tablolar, 1 GB'lik dosyalarda sakland iin, dosya
sistemi snrlarnin bir nemi yoktur.
Tablo ve kolon says byklkleri, n tanml blok bykl 32k ya karlarak
arttrlabilir.
4.6) Tipik bir metin dosyasndaki veriyi saklamak iin ne kadar disk alan gereklidir?
Bir PostgreSQL veritaban, veriyi "flat" metin dosyasnda saklamak iin gereken
alann 5 kat fazla disk alanna gereksinim duyabilir.
Her satrnda bir tamsay ve metin (text) ieren, 100.000 satrlk bir dosya dnn.
Her satrn ortalama 20 byte olduunu farzedelim. Metin dosyas 2.8 MB olacaktr. Bu veriyi
tutan PostgreSQL veritaban yaklak 6.4 MB yer kaplayacaktr.
36 byte: Her bir satr baslg (yaklasik)
+ 24 byte: Bir tamsay (int) alani ve bir metin (text) alan
+ 4 byte: Sayfada tuple a pointer
----------------------------------------
64 byte -> kayt basna
PostgreSQL'de data page bykl 8192 byte (8k)dir, dolaysyla:
8192 byte -> page basna
------------------------- = Her bir veritabani page i bana 128 satr (yaklak)
Satr basna 64 byte
100000 veri satr
-------------------- = 782 veritaban sayfas
128 satr
782 veritaban sayfas * sayfa bana 8192 byte = 6,406,144 bytes (6.4 MB)
Indexler cok fazla yere gereksinim duymazlar, ama indexlenmis veriyi tutacaklarndan
byk olabilirler.
NULL deerler bitmapler iinde tutulur; dolaysyla ok az yer kaplarlar.
4.7) Veritabannda hangi tablo ya da indexlerin tanmlandgn nasil grebilirim?
psql, bu tr bilgileri gstermek iin, \ ile balayan bir ok komut sunmaktadr.
\? komutu ile bu komutlar grebilirsiniz. Ayrca, bunlar aklayan ve pg_ ile balayan
ok sayda sistem tablosu bulunmaktadr. Ayn zamanda, psql -l ile tm veritabanlarn
listeyelebirsiniz.
Ayrca, pgsql/src/tutorial/syscat.source kodunu inceleyebilirsiniz. Bu dosya, veritaban
sistem dosyalarindan bilgiyi almak iin gereksinim duyulan bir ok SELECTleri gsterir.
4.8) Sorgularm cok yava, ya da indexlerimi kullanmyorlar. Neden?
Indexes are not automatically used by every query. Indexes are only used if the table is larger than a minimum size,
and the query selects only a small percentage of the rows in the table. This is because the random disk access caused
by an index scan can be slower than a straight read through the table, or sequential scan.
To determine if an index should be used, PostgreSQL must have statistics about the table. These statistics are
collected using VACUUM ANALYZE, or simply ANALYZE. Using statistics, the optimizer knows how many rows are in the
table, and can better determine if indexes should be used. Statistics are also valuable in determining optimal join
order and join methods. Statistics collection should be performed periodically as the contents of the table change.
Indexes are normally not used for ORDER BY or to perform joins. A sequential scan followed by an explicit sort is
usually faster than an index scan of a large table.
However, LIMIT combined with ORDER BY often will use an index because only a small portion of the table is returned.
In fact, though MAX() and MIN() don't use indexes, it is possible to retrieve such values using an index with ORDER
BY and LIMIT:
SELECT col
FROM tab
ORDER BY col [ DESC ]
LIMIT 1;
Eer optimizer'in sequential scan ileminde hata yaptn dnyorsanz, SET enable_seqscan TO 'off' 'u kullannz
ve index scan'in hala hzl olup olmadn grmek iin testler yapnz.
LIKE ya da ~ gibi operatorler kullaniyorsanz, indeksler sadece aadaki koullarda kullanlabilir:
* Arama dizininin ba, dizinin ba ile balanmaldr. Yani,
o LIKE sorgular % ile balamamaldr.
o Dzenli ifade sorgular ^ ie balamamaldr.
* Arama metni bir karakter snf ile balayamaz. rnek: [a-e]
* ILIKE ve ~* gibi byk/kk harfe duyarsz aramalar indekslerden yararlanmazlar. Onun yerine, blm 4.12'de
anlatlan fonksiyonel indeksleri kullanabilirsiniz.
* initdb srasnda ntanml C localei kullanlmaldr.
4.9) query-optimizer in sorgularm nasl deerlendirdiini, ileme soktuunu nasl grebilirim?
EXPLAIN yardm sayfasna baknz.
4.10) R-tree index nedir?
An R-tree index is used for indexing spatial data. A hash index can't handle range searches. A B-tree index only
handles range searches in a single dimension. R-trees can handle multi-dimensional data. For example, if an R-tree
index can be built on an attribute of type point, the system can more efficiently answer queries such as "select all
points within a bounding rectangle."
The canonical paper that describes the original R-tree design is:
Guttman, A. "R-trees: A Dynamic Index Structure for Spatial Searching." Proceedings of the 1984 ACM SIGMOD Int'l Conf
on Mgmt of Data, 45-57.
Bu paperi, Stonebraker'n "Readings in Database Systems" kitabnda bulabilirsiniz.
Built-in R-trees can handle polygons and boxes. In theory, R-trees can be extended to handle higher number of
dimensions. In practice, extending R-trees requires a bit of work and we don't currently have any documentation on
how to do it.
4.11) Genetic Query Optimizer nedir?
GEQO modl, Genetic Algorith(GA) kullanlarak tablolar birletirildiinde sorgu optimizasyonunu hzlandrr.
It allows the handling of large join queries through nonexhaustive search.
4.12) Dzenli ifade (Regular Expression) aramalarn ve byk/kk harfe duyarsz aramalar nasil yapabilirim?
Bu byk(kk harfe duyarl aramalar iin indeksi nasil kullanabilirim?
~ operatr dzenli ifade elemesi ve ~* byk/kk harfe duyarsz dzenli ifade elemesi yapar.
Byk/kk harfe duyarl olan LIKE'in byk/kk harfe duyarsz olan biini ILIKE'tr ve PostgreSQL
7.1 srm ile birlikte gelmitir.
Byk-kk harfe duyarsz eitlik karlatrmalar aadaki gibi ifade edilir:
SELECT *
FROM tab
WHERE lower(col) = 'abc'
Bu standart bir indeks yaratmayacaktr. Ancak eer fonksiyonel bir indeks yaratrsanz; o kullanlacaktr:
CREATE INDEX tabindex on tab (lower(col));
4.13) Bir sorguda, bir alanin "NULL" oldugunu nasil ortaya karabilirim?
Kolonu, IS NULL ve IS NOT NULL ile test edebilirsiniz.
4.14) esitli karakter tipleri arasndaki farklar nelerdir?
Veri Tipi Ad Not
--------------------------------------------------
VARCHAR(n) varchar boyut en byk uzunluu verir; sadece verilen kadar veri tutulur.
CHAR(n) bpchar belirtilen uzunlupa kadar sonuna boluk eklenir.
TEXT text uzunlukta herhangi bir st snr yoktur.
BYTEA bytea variable-length byte array (null-byte safe)
"char" char bir karakter
adlar (internal name) sistem kataloglarn ve baz hata meajlarn incelerken greceksiniz.
lk drt veri tipi "varlena" tipidir (yani, diskteki ilk 4 bayt uzunluktur; devam da veridir.) Dolaysyla,
Bylece, kullanlan gerek alan, belirtilen alandan biraz daha byktr. Ancak, bu veri tipleri, sktrlmaya tabi
tutulabilir; dolaysyla disk alan beklenilenden kck olabilir. VARCHAR(n) bykl artabilen ama en byk
uzunluu snrl oan verileri saklamak iin en uygun yntemdir. TEXT, 1 GB bykle kadar olan verileri tutmak iin
kullanlr.
CHAR(n), ayn uzunluktaki dizilerin saklanmas iin kullanmr. CHAR(n) belirtilen uzunlua kadar boluk ile
doldurur; ancak VARCHAR(n) sadece verilen karakterleri saklar.BYTEA binary veri saklamak iindir; ayrca "NULL" bayt
ieren deerleri de saklar. Burada anlatlan veri tipi de benzer baarm karakteristiklere sahiptir.
4.15.1) Nasil serial/otomatik artan(auto-incrementing) bir alan yaratabilirim?
PostgreSQL'de SERIAL veri tipi vardr. Bu veri tipi bir sequence ve kolon zerinde bir indeks yaratr.
rnek, aadaki sorgu:
CREATE TABLE person (
id SERAL,
name TEXT
);
buna evrilir:
CREATE SEQUENCE person_id_seq;
CREATE TABLE person (
id NT4 NOT NULL DEFAULT nextval('person_id_seq'),
name TEXT
);
CREATE UNIQUE NDEX person_id_key ON person ( id );
Sequenceler hakknda daha fazla bilgi iin create_sequence yardm sayfasna bakabilirsiniz. Her satrn OID alann
tekil bir say olarak alabilirsiniz. Ancak, veritabannzn dump'n alp yeniden yklerseniz, OID deerlerini
koruyabilmek iin pg_dump'n -o parametresini ya da "COPY WITH OIDS" seeneini kullanmanz gerekecektir.
4.15.2) SERIAL giriinin degerini nasil alabilirim?
One approach is to retrieve the next SERIAL value from the sequence object with the nextval() function before
inserting and then insert it explicitly. Using the example table in 4.15.1, an example in a pseudo-language would
look like this:
new_id = execute("SELECT nextval('person_id_seq')");
execute("INSERT INTO person (id, name) VALUES (new_id, 'Blaise Pascal')");
You would then also have the new value stored in new_id for use in other queries (e.g., as a foreign key to the
person table). Note that the name of the automatically created SEQUENCE object will be named
<table>_<serialcolumn>_seq, where table and serialcolumn are the names of your table and your SERIAL column,
respectively.
Alternatif olarak, atanm SERIAL deerini, deer girildikten sonra currval() fonksiyonu ile alabilirsiniz:
execute("INSERT INTO person (name) VALUES ('Blaise Pascal')");
new_id = execute("SELECT currval('person_id_seq')");
Son olarak, n tanml deeri bulmak iin INSERT ifadesinden dnen OID deerini kullanabilirsiniz; ancak bu
en az tanabilir zm olacaktr. Perl'de, Edmund Mergl'in DBD:Pg mdl ile birlikte DBI kullanarak, oid deeri
$sth->execute() altrldktan sonra $sth->(pg_oid_status) ile alnabilir.
4.15.3) currval() ve nextval() diger kullanicilara sorun yaratmaz m?
Hayr. curval(), tm kullanclar degil, backend tarafndan atanan geerli
degeri dndrr.
4.15.4) Neden sequence saylarn transaction ileminin iptalinden sonra yeniden kullanlyor? Neden sequence/SERIAL
kolonumdaki saylarda atlamalar oluyor?
Uyumluluu arttrmak iin, sequence deerleri alan transactionlara gerektii ekilde aktarlr ve transaction
bitene kadar o deer kilitlenmez. Bu, iptal edilen transaction ilemleri nedeniyle boluklara neden olur.
4.16) OID nedir? TID nedir?
ODs are PostgreSQL's answer to unique row ids. Every row that is
created in PostgreSQL gets a unique OD. All ODs generated during
initdb are less than 16384 (from backend/access/transam.h). All
user-created ODs are equal to or greater than this. By default, all
these ODs are unique not only within a table or database, but unique
within the entire PostgreSQL installation.
PostgreSQL uses ODs in its internal system tables to link rows
between tables. These ODs can be used to identify specific user rows
and used in joins. t is recommended you use column type OD to store
OD values. You can create an index on the OD field for faster
access.
ODs are assigned to all new rows from a central area that is used by
all databases. f you want to change the OD to something else, or if
you want to make a copy of the table, with the original ODs, there is
no reason you can't do it:
CREATE TABLE new_table(old_oid oid, mycol int);
SELECT old_oid, mycol NTO new FROM old;
COPY new TO '/tmp/pgtable';
DELETE FROM new;
COPY new WTH ODS FROM '/tmp/pgtable';
ODs are stored as 4-byte integers, and will overflow at 4 billion. No
one has reported this ever happening, and we plan to have the limit
removed before anyone does.
TIDs are used to identify specific physical rows with block and offset
values. TIDs change after rows are modified or reloaded. They are used
by index entries to point to physical rows. 4.17) What is the meaning
of some of the terms used in PostgreSQL? Some of the source code and
older documentation use terms that have more common usage. Here are
some: * table, relation, class * row, record, tuple * column, field,
attribute * retrieve, select * replace, update * append, insert * OID,
serial value * portal, cursor * range variable, table name, table
alias A list of general database terms can be found at:
http://hea-www.harvard.edu/MST/simul/software/docs/pkgs/pgsql/glossary
/glossary.html 4.18) Why do I get the error /"ERROR: Memory exhausted
in AllocSetAlloc()"/? You probably have run out of virtual memory on
your system, or your kernel has a low limit for certain resources. Try
this before starting /postmaster/: ulimit -d 262144 limit datasize
256m Depending on your shell, only one of these may succeed, but it
will set your process data segment limit much higher and perhaps allow
the query to complete. This command applies to the current process,
and all subprocesses created after the command is run. If you are
having a problem with the SQL client because the backend is returning
too much data, try it before starting the client. 4.19) How do I tell
what PostgreSQL version I am running? From /psql/, type |SELECT
version();| 4.20) Why does my large-object operations get /"invalid
large obj descriptor"/? You need to put |BEGIN WORK| and |COMMIT|
around any use of a large object handle, that is, surrounding
|lo_open| ... |lo_close.| Currently PostgreSQL enforces the rule by
closing large object handles at transaction commit. So the first
attempt to do anything with the handle will draw /invalid large obj
descriptor/. So code that used to work (at least most of the time)
will now generate that error message if you fail to use a transaction.
If you are using a client interface like ODBC you may need to set
|auto-commit off.| 4.21) How do I create a column that will default to
the current time? Use /CURRENT_TIMESTAMP/: |CREATE TABLE test (x int,
modtime timestamp DEFAULT CURRENT_TIMESTAMP ); | 4.22) Why are my
subqueries using |IN| so slow? Currently, we join subqueries to outer
queries by sequentially scanning the result of the subquery for each
row of the outer query. If the subquery returns only a few rows and
the outer query returns many rows, |IN| is fastest. To speed up other
queries, replace |IN| with |EXISTS|: SELECT * FROM tab WHERE col IN
(SELECT subcol FROM subtab); to: SELECT * FROM tab WHERE EXISTS
(SELECT subcol FROM subtab WHERE subcol = col); For this to be fast,
|subcol| should be an indexed column. This preformance problem will be
fixed in 7.4. 4.23) How do I perform an outer join? PostgreSQL
supports outer joins using the SQL standard syntax. Here are two
examples: SELECT * FROM t1 LEFT OUTER JOIN t2 ON (t1.col = t2.col); or
SELECT * FROM t1 LEFT OUTER JOIN t2 USING (col); These identical
queries join t1.col to t2.col, and also return any unjoined rows in t1
(those with no match in t2). A RIGHT join would add unjoined rows of
t2. A FULL join would return the matched rows plus all unjoined rows
from t1 and t2. The word OUTER is optional and is assumed in LEFT,
RIGHT, and FULL joins. Ordinary joins are called INNER joins. In
previous releases, outer joins can be simulated using UNION and NOT
IN. For example, when joining /tab1/ and /tab2/, the following query
does an /outer/ join of the two tables: SELECT tab1.col1, tab2.col2
FROM tab1, tab2 WHERE tab1.col1 = tab2.col1 UNION ALL SELECT
tab1.col1, NULL FROM tab1 WHERE tab1.col1 NOT IN (SELECT tab2.col1
FROM tab2) ORDER BY col1 4.24) How do I perform queries using multiple
databases? There is no way to query a database other than the current
one. Because PostgreSQL loads database-specific system catalogs, it is
uncertain how a cross-database query should even behave.
/contrib/dblink/ allows cross-database queries using function calls.
Of course, a client can make simultaneous connections to different
databases and merge the results on the client side. 4.25) How do I
return multiple rows or columns from a function? In 7.3, you can
easily return multiple rows or columns from a function,
http://techdocs.postgresql.org/guides/SetReturningFunctions
techdocs.postgresql.org/guides/SetReturningFunctions>. 4.26) Why can't
I reliably create/drop temporary tables in PL/PgSQL functions?
PL/PgSQL caches function contents, and an unfortunate side effect is
that if a PL/PgSQL function accesses a temporary table, and that table
is later dropped and recreated, and the function called again, the
function will fail because the cached function contents still point to
the old temporary table. The solution is to use EXECUTE for temporary
table access in PL/PgSQL. This will cause the query to be reparsed
every time. 4.27) What replication options are available? There are
several master/slave replication options available. These allow only
the master to make database changes and the slave can only do database
reads. The bottom of
http://gborg.PostgreSQL.org/genpage?replication_research
gborg.PostgreSQL.org/genpage?replication_research> lists them. A
multi-master replication solution is being worked on at
http://gborg.PostgreSQL.org/project/pgreplication/projdisplay.php.
4.28) What encryption options are available? * /contrib/pgcrypto/
contains many encryption functions for use in SQL queries. * The only
way to encrypt transmission from the client to the server is by using
/hostssl/ in /pg_hba.conf/. * Database user passwords are
automatically encrypted when stored in version 7.3. In previous
versions, you must enable the option /PASSWORD_ENCRYPTION/ in
/postgresql.conf/. * The server can run using an encrypted file
system.
----------------------------------------------------------------------
-- Extending PostgreSQL 5.1) I wrote a user-defined function. When I
run it in /psql/, why does it dump core? The problem could be a number
of things. Try testing your user-defined function in a stand-alone
test program first. 5.2) How can I contribute some nifty new types and
functions to PostgreSQL? Send your extensions to the /pgsql-hackers/
mailing list, and they will eventually end up in the /contrib//
subdirectory. 5.3) How do I write a C function to return a tuple? In
versions of PostgreSQL beginning with 7.3, table-returning functions
are fully supported in C, PL/PgSQL, and SQL. See the Programmer's
Guide for more information. An example of a table-returning function
defined in C can be found in /contrib/tablefunc/. 5.4) I have changed
a source file. Why does the recompile not see the change? The
/Makefiles/ do not have the proper dependencies for include files. You
have to do a /make clean/ and then another /make/. If you are using
GCC you can use the /--enable-depend/ option of /configure/ to have
the compiler compute the dependencies automatically.
values. TDs change after rows are modified or reloaded. They are used
by index entries to point to physical rows.
4.17) PostgreSQL'de kullanlan baz terimlerin anlamlar nelerdir?
Kaynak kodun bir ksm ve eski belgeler, daha genis kullanm alan olan terimleri
kullanrlar. Bunlarn bazlar:
* table, relation, class
* row, record, tuple
* column, field, attribute
* retrieve, select
* replace, update
* append, insert
* OID, serial value
* portal, cursor
* range variable, table name, table alias
Genel veritaban terimleri,
http://hea-www.harvard.edu/MST/simul/software/docs/pkgs/pgsql/glossary/glossary.html
adresinde bulunabilir.
4.18) Neden "ERROR: Memory exhausted in AllocSetAlloc()"? hatasn alyorum?
Sisteminizde sanal belleginizi tketmis olabilirsiniz, ya da ekirdeginiz
belli kaynaklar icin dk bir snra sahip olabilir. postmasteri baslatmadan nce
asagidakileri deneyebilirsiniz:
ulimit -d 262144
limit datasize 256m
Kabuunuza bal olarak, bunlardan sadece biri olumlu sonu verecektir, ama
bu ilem veri segment snrnz arttracak, ve belki de sorgunuzun tamamlanmasn
saglayacaktr. Bu komut, varolan isleme (current process) ve komut alstrldktan
sonraki tm alt islemlere uygulanir. Eger SQL istemcinizle, backendin ok fazla veri
dndrmesi nedeniyle bir sorun yasyorsanz, bunu istemciyi baslatmadan nce deneyiniz.
4.19) Hangi PostgreSQL srmn alstrdgm nasil grebilirim?
psql arabiriminde, select version(); yaznz.
4.20) Neden large-object islemlerim, "invalid large obj descriptor"? hatasn veriyor?
Large object islemlerinizin uclarina, yani lo_open ... lo_close komutlarnn evresine,
BEGIN WORK ve COMMIT koymanz gerekmektedir;
Eger ODBC gibi bir istemci arabirimi kullanyorsanz, auto-commit'i kapatmanz gerekebilir.
4.21) Su andaki zaman ntanml deger olarak kabul eden How do create a column that will default to the current time?
Alttakini kullanabilirsiniz:
CURRENT_TIMESTAMP:
CREATE TABLE test (x int, modtime timestamp DEFAULT CURRENT_TIMESTAMP );
4.22) Neden IN kullanan subquerylerim ok yavas?
Currently, we join subqueries to outer queries by sequentially scanning the result of the subquery for
each row of the outer query. IN' i EXISTS ile deitirerek bir zme ulalabilir.
SELECT *
FROM tab
WHERE col1 N (SELECT col2 FROM TAB2)
to:
SELECT *
FROM tab
WHERE EXSTS (SELECT col2 FROM TAB2 WHERE col1 = col2)
Bu snrlamay ilerdeki srmlerimizde dzeltmeyi planlamaktayz.
4.23) Outer join islemini nasil yapabilirim?
PostgreSQL outer joins islemlerini SQL standartlarn kullanarak gereklestirmektedir.
Asagida 2 rnek bulunmaktadr:
SELECT *
FROM t1 LEFT OUTER JON t2 ON (t1.col = t2.col);
ya da
SELECT *
FROM t1 LEFT OUTER JON t2 USNG (col);
Bu zdes sorgular t1.col ' i t2.col'ye join ederler ve ayn zamanda t1'deki unjoined satrlar
(t2'de eslenmenis olanlarla) dndrrler. RGHT JON t2'nin unjoined satrlarn ekleyecektir.
Bir FULL join, elemi btn satrlar ve t1 ile t2'den tm balanmam (unjoined) satrlar alr.
OUTER szc seimseldir ve LEFT, RIGHT ve FULL join ilemlerinde olduu kabul edilir. Sradan
join ilemleri INNER join olarak adlandrlr.
nceki srmlerde, OUTER JOINler UNION ve NOT IN kullanlarak simle edilebiliyordu. rnein, tab1
ve tab2'yi birletirirken, aadaki sorgu iki tablonun dtan balanmasn salar:
SELECT tab1.col1, tab2.col2
FROM tab1, tab2
WHERE tab1.col1 = tab2.col1
UNION ALL
SELECT tab1.col1, NULL
FROM tab1
WHERE tab1.col1 NOT N (SELECT tab2.col1 FROM tab2)
ORDER BY col1
4.24) Ayni andan birden fazla veritabaninda nasil islem yapabilirim?
Mevcut veritabannz dsndaki baska bir veritabannz sorgulamanzn bir yolu bulunmamaktadr.
bunun nedeni, PostgreSQL'in veritabanna zel sistem kataloglar yklemesidir. Bu nedenle,
cross-database bir sorgunun nasil davranacagn kestirmek zordur.
contrib/dblink fonksiyon arlarn kullanarak cross-database sorgulara izin verid. Tabii ki,
bir istemci degisik veritabanlarna ayn anda erisim saglayabilir ve bilgiyi bu sekilde
birlestirebilir.
4.25) Bir fonksiyondan nasl oklu satr ya da kolon dndrebilirim?
7.3 srmnde, bir fonksiyondan kolaylkla oklu satr ya da stun dndrebilirsiniz.
http://techdocs.postgresql.org/guides/SetReturningFunctions.
4.26) Neden Pl/PgSQL fonksiyonlar iinden gvenli bir ekilde tablo yaratma/kaldrma ilemlerini yapamyoruz?
PL/PgSQL fonksiyon ierikleri cacheler. Bunun istenmeyen bir taraf, eer bir PL/PgSQL fonksiyonu geici bir
tabloya eriiyorsa ve bu tablo ileride kaldrlp yeniden oluturulduktan sonra fonksiyon yeniden arlrsa,
fonksiyon almayacaktr; nk cachelenmi fonksiyon hala eski geici tabloyu gsteriyor olacaktr. zm,
geici tablo eriimleri iin PL/PgSQL'de EXECUTE kullanmaktr. Bu, sorgunun her seferinde yeniden ilenmesini
salayacaktr.
4.27) Hangi replikasyon seenekleri bulunmaktadr?
eitli master/slave replikasyon seenekleri bulunmaktadr. Bunlar master veritabannn veritaban deiikliklerini
yaparken, slave sunucunun sadece veritabannda okuma yapmasna izin verir.
http://gborg.PostgreSQL.org/genpage?replication_research sayfasnn altnda bunlarn listesini bulabilirsiniz.
http://gborg.PostgreSQL.org/project/pgreplication/projdisplay.php adresinde, oklu-master replikasyon zm
zerinde allyor.
4.28) Hangi ifreleme seenekleri bulunmaktadr?
* contrib/pgcrypto SQL sorgularnda kullanlabilmesi iin ifreleme fonksiyonlar iermektedir.
* stemciden sunucuya iletiimi ifrelemenin tek yolu, pg_hba.conf iinde hostssl kullanmaktr.
* Veritaban kullanc ad ve ifreleri 7.3 srm ile birlikte otomatik olarak ifrelenirler. nceki
srmlerde, postgresql.conf iindeki PASSWORD_ENCRYPTION seeneini aktif hale getirmeniz gerekmektedir.
* Sunucunun kendisini ifreli dosya sistemi zerinde altrabilirsiniz.
_________________________________________________________________
PostgreSQL zelliklerini Geniletmek
5.1) Kullanici-tanimli bir fonksiyon yazdim. psql'de alistirdigim zaman neden core dump ediyor?
Sorunun nedeni birden fazla sey olabilir. Kullanici-tanimli fonksiyonunuzu stand-alone bir programda
calistirmayi deneyiniz.
5.2) PostgreSQL'e nasil yeni tipler/fonksiyonlar ekleyeiblirim?
alsmalarnz pgsql-hackers e-posta listesine gnderiniz. Kodunuz incelendikten sonra
/contrib dizinine konacaktr.
5.3) Bir tuple dondrmek icin bir C fonksiyonunu nasil yazarm?
PostgreSQL 7.3 srm ile birlikte, C, PL/PgSQL ve SQL kullanlarak tablo-dndren
fonksiyonlar tamamen desteklenmektedir. Ayrntl bilgi iin "Programmer's Guide" a
bakabilrisiniz. Bir rnei contrib/tablefunc iinde bulabilirsiniz.
5.4) Bir kaynak dosyasnda deiiklik yaptm. Yeniden derlememe ramen deiiklik
geerli olmuyor. Neden?
Makefile'lar include dosyalar iin tam bir bamllk iermezler.
ncelikle make clean, ardndan da baska bir make ilemi yapmanz gerekir.
GCC kullanyorsaniz, configure betiinin --enable-depend seeneini, derleyicinin
bamllklar otomatik olarak hesaplamas iin kullanabilirsiniz.
doc/src/FAQ/FAQ_turkish.html
View file @ 6b8f6a65
PostgreSQL iin Ska Sorulan Sorular (SSS)
Son güncelleme : 19 Mayýs 2003 Pazartesi - 03:05:21
Son gncelleme : 26 Temmuz 2003 Cumartesi - 18:32:11
Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us
<mailto:pgman@candle.pha.pa.us>)
Çeviren : Devrim GÜNDÜZ (devrim@gunduz.org <mailto:devrim@gunduz.org>)
Nicolai Tufar (ntufar@yahoo.com <mailto:ntufar@yahoo.com>)
evirenler : Devrim Gndz (devrim@gunduz.org <mailto:devrim@gunduz.org>)
Nicholas Morris Tufar (ntufar@yahoo.com <mailto:ntufar@yahoo.com>)
Volkan Yazc (volkany@celiknet.com <mailto:volkany@celiknet.com>)
Bu belgenin en gncel hali,
http://www.PostgreSQL.org/docs/faqs/FAQ_turkish.html ve
http://www.PostgreSQL.org/docs/faqs/FAQ_turkish.html
<http://www.postgresql.org/docs/faqs/FAQ_turkish.html> ve
http://www.gunduz.org/seminer/pg/FAQ_turkish adreslerinde grlebilir.
Platforma özel sorularýnýz,http://www.PostgreSQL.org/docs/index.html
adresinde yanýtlanýr..
Platforma zel sorularnz, http://www.PostgreSQL.org/docs/index.html
<http://www.postgresql.org/docs/index.html> adresinde yantlanr.
------------------------------------------------------------------------
......@@ -28,137 +30,141 @@ adresinde yan
1.5 <#1.5>) PostgreSQL'i nereden indirebilirim?
1.6 <#1.6>) Destei nereden alabilirim?
1.7 <#1.7>) En son srm nedir?
1.8 <#1.8>) Hangi belgelere ulasabilirim?
1.8 <#1.8>) Hangi belgelere ulaabilirim?
1.9 <#1.9>) Bilinen hatalar ya da eksik zelliklere nereden ulasabilirim?
1.10 <#1.10>) Nasl SQL renebilirim?
1.11 <#1.11>) PostgreSQL 2000 ylna uyumlu mudur?
1.12 <#1.12>) Gelitirme takmna nasl katlabilirim??
1.13 <#1.13>) Bir hata raporunu nasl gnderebilirim?
1.14 <#1.14>) PostgreSQL, diger VTYS(DBMS lerle nasýl karþýlaþtýrýlabilir?
1.14 <#1.14>) PostgreSQL, dier VTYS(DBMS) lerle nasl karlatrlabilir?
1.15 <#1.15>) PostgreSQL'e maddi adan nasl destek olabilirim?
Kullanc/istemci Sorular
2.1 <#2.1>) Are there ODBC drivers for PostgreSQL?
2.2 <#2.2>) What tools are available for using PostgreSQL with Web pages?
2.3 <#2.3>) Does PostgreSQL have a graphical user interface?
2.4 <#2.4>) What languages are available to communicate with PostgreSQL?
Administrative Questions
3.1 <#3.1>) How do I install PostgreSQL somewhere other than
//usr/local/pgsql/?
3.2 <#3.2>) When I start /postmaster/, I get a /Bad System Call/ or core
dumped message. Why?
3.3 <#3.3>) When I try to start /postmaster/, I get /IpcMemoryCreate/
errors. Why?
3.4 <#3.4>) When I try to start /postmaster/, I get /IpcSemaphoreCreate/
errors. Why?
3.5 <#3.5>) How do I control connections from other hosts?
3.6 <#3.6>) How do I tune the database engine for better performance?
3.7 <#3.7>) What debugging features are available?
3.8 <#3.8>) Why do I get /"Sorry, too many clients"/ when trying to connect?
3.9 <#3.9>) What is in the /pgsql_tmp/ directory?
3.10 <#3.10>) Why do I need to do a dump and restore to upgrade
PostgreSQL releases?
Operational Questions
4.1 <#4.1>) What is the difference between binary cursors and normal
cursors?
4.2 <#4.2>) How do I SELECT only the first few rows of a query?
4.3 <#4.3>) How do I get a list of tables or other things I can see in
/psql/?
4.4 <#4.4>) How do you remove a column from a table?
4.5 <#4.5>) What is the maximum size for a row, a table, and a database?
4.6 <#4.6>) How much database disk space is required to store data from
a typical text file?
4.7 <#4.7>) How do I find out what tables, indexes, databases, and users
are defined?
4.8 <#4.8>) My queries are slow or don't make use of the indexes. Why?
4.9 <#4.9>) How do I see how the query optimizer is evaluating my query?
4.10 <#4.10>) What is an R-tree index?
4.11 <#4.11>) What is the Genetic Query Optimizer?
4.12 <#4.12>) How do I perform regular expression searches and
case-insensitive regular expression searches? How do I use an index for
case-insensitive searches?
4.13 <#4.13>) In a query, how do I detect if a field is NULL?
4.14 <#4.14>) What is the difference between the various character types?
4.15.1 <#4.15.1>) How do I create a serial/auto-incrementing field?
4.15.2 <#4.15.2>) How do I get the value of a SERIAL insert?
4.15.3 <#4.15.3>) Don't /currval()/ and /nextval()/ lead to a race
condition with other users?
4.15.4 <#4.15.4>) Why aren't my sequence numbers reused on transaction
abort? Why are there gaps in the numbering of my sequence/SERIAL column?
4.16 <#4.16>) What is an OID? What is a TID?
4.17 <#4.17>) What is the meaning of some of the terms used in PostgreSQL?
4.18 <#4.18>) Why do I get the error /"ERROR: Memory exhausted in
AllocSetAlloc()"/?
4.19 <#4.19>) How do I tell what PostgreSQL version I am running?
4.20 <#4.20>) Why does my large-object operations get /"invalid large
obj descriptor"/?
4.21 <#4.21>) How do I create a column that will default to the current
time?
4.22 <#4.22>) Why are my subqueries using |IN| so slow?
4.23 <#4.23>) How do I perform an outer join?
4.24 <#4.24>) How do I perform queries using multiple databases?
4.25 <#4.25>) How do I return multiple rows or columns from a function?
4.26 <#4.26>) Why can't I reliably create/drop temporary tables in
PL/PgSQL functions?
4.27 <#4.27>) What replication options are available?
4.28 <#4.28>) What encryption options are available?
Extending PostgreSQL
5.1 <#5.1>) I wrote a user-defined function. When I run it in /psql/,
why does it dump core?
5.2 <#5.2>) How can I contribute some nifty new types and functions to
PostgreSQL?
5.3 <#5.3>) How do I write a C function to return a tuple?
5.4 <#5.4>) I have changed a source file. Why does the recompile not see
the change?
2.1 <#2.1>) PostgreSQL iin ODBC srcleri var m ?
2.2 <#2.2>) PostgreSQL'i web sayfalarnda kullanabilmek iin hangi
aralar bulunmaktadr ?
2.3 <#2.3>) PostgreSQL'in grafik kullanc arabirimi var mdr?
2.4 <#2.4>) PostgreSQL ile iletiimi kurabilmek iin hangi dilleri
kullanabilirim?
Ynetimsel Sorular
3.1 <#3.1>) PostgreSQL'i //usr/local/pgsql/ dizininden baka dizinlere
nasl kurabilirim??
3.2 <#3.2>) /Postmaster/' balattmda /Bad System Call/ ya da core
dumped mesaj alyorum. Neden?
3.3 <#3.3>) /Postmaster/' balattmda, /IpcMemoryCreate/ hatas
alyorum. Neden?
3.4 <#3.4>) /Postmaster/, balattmda, /IpcSemaphoreCreate hatas/
alyorum. Neden?
3.5 <#3.5>) Dier bilgisayarlarn benim PostgreSQL veritaban sunucuma
balantlarn nasl kontrol edebilirim?
3.6 <#3.6>) Veritaban motorunu daha iyi baarm icin nasl ayarlayabilirim?
3.7 <#3.7>) Hangi hata ayklama zellikleri bulunmaktadr?
3.8 <#3.8>) Balanmaya alrken, neden "/Sorry, too many clients/"
hatasn alyorum?
3.9 <#3.9>) /pgsql_tmp/dizinin iindeki dosyalar nelerdir?
3.10 <#3.10>) PostgreSQL srmlerini ykselmek iin neden bir
dump/reload ilemi gerekletirmek zorundaym?
letimsel Sorular
4.1 <#4.1>) Binary cursor ve normal cursor arasndaki fark nedr?
4.2 <#4.2>)Sorgunun sadece ilk birka satrn nasl SELECT edebilirim?
4.3 <#4.3>) /psql/'in iinde grdgm tablolarin ya da dier eylerin
listesini nasl alabilirim?
4.4 <#4.4>)Bir tablodan bir kolonu nasl kaldrabilirim?
4.5 <#4.5>)Bir satr, tablo ve veritaban icin en fazla byklk nedir?
4.6 <#4.6>) Tipik bir metin dosyasndaki veriyi saklamak iin ne kadar
disk alan gereklidir?
4.7 <#4.7>) Veritabannda hangi tablo ya da indexlerin tanmlandgn
nasil grebilirim?
4.8 <#4.8>) Sorgularm cok yavas, ya da indexlerimi kullanmiyorlar. Neden?
4.9 <#4.9>) Query-optimizer in sorgularm nasl deerlendirdigini,
ileme soktuunu nasl grebilirim?
4.10 <#4.10>) R-tree index nedir?
4.11 <#4.11>) Genetic Query Optimizer nedir?
4.12 <#4.12>) Dzenli ifade (Regular Expression) aramalarn ve
byk/kk harfe duyarsz aramalar nasil yapabilirim? Bu byk(kk
harfe duyarl aramalar iin indeksi nasil kullanabilirim?
4.13 <#4.13>) Bir sorguda, bir alann NULL olduunu nasl ortaya
karabilirim?
4.14 <#4.14>) esitli karakter tipleri arasndaki farklar nelerdir?
4.15.1 <#4.15.1>) Nasl serial/otomatik artan(auto-incrementing) bir
alan yaratabilirim?
4.15.2 <#4.15.2>) Serial giriinin deerini nasl alabilirim?
4.15.3 <#4.15.3>) /currval()/ ve /nextval()/ dier kullanclara sorun
yaratmaz m?>
4.15.4 <#4.15.4>) Neden sequence saylarn transaction ileminin
iptalinden sonra yeniden kullanlyor? Neden sequence/SERIAL kolonumdaki
saylarda atlamalar oluyor?
4.16 <#4.16>) OID nedir? TID nedir?
4.17 <#4.17>) PostgreSQL' de kullanlan baz terimlerin anlamlar nelerdi?
4.18 <#4.18>) Neden /"ERROR: Memory exhausted in AllocSetAlloc()"/
hatasn alyorum?
4.19 <#4.19>) Hangi PostgreSQL srmn alstrdm nasl grebilirim??
4.20 <#4.20>) Neden large-object ilemlerim, /"invalid large obj
descriptor"/ hatasn veriyor?
4.21 <#4.21>) u andaki zaman ntanml deer olarak kabul eden kolonu
nasl yaratrm?
4.22 <#4.22>) Neden |IN| kullanan subquerylerim ok yava?
4.23 <#4.23>) Outer join ilemini nasl yapabilirim?
4.24 <#4.24>) Ayn anda birden fazla veritabannda nasl ilem yapabilirim?
4.25 <#4.25>) Bir fonksiyondan nasl oklu satr ya da kolon
dndrebilirim??
4.26 <#4.26>) Neden Pl/PgSQL fonksiyonlar iinden gvenli bir ekilde
tablo yaratma/kaldrma ilemlerini yapamyoruz?
4.27 <#4.27>) Hangi replikasyon seenekleri bulunmaktadr?
4.28"D <#4.28>) Hangi ifreleme seenekleri bulunmaktadr?
PostgreSQL zelliklerini Geniletmek
5.1 <#5.1>) Kullanc-tanml bir fonksiyon yazdm. /psql/'de
altrdm zaman neden core dump ediyor?
5.2 <#5.2>) PostgreSQL'e nasl yeni veri tipleri/fonksiyonlar ekleyebilirim?
5.3 <#5.3>) Bir tuple dndrmek iin bir C fonksiyonunu nasl yazarm?
5.4 <#5.4>) Bir kaynak dosyasnda deisiklik yaptm. Yeniden derlememe
ramen deiiklik geerli olmuyor. Neden??
------------------------------------------------------------------------
General Questions
Genel Sorular
1.1) What is PostgreSQL? How is it pronounced?
PostgreSQL is pronounced /Post-Gres-Q-L/.
1.1) PostgreSQL nedir? Nasl okunur?
PostgreSQL is an enhancement of the POSTGRES database management system,
a next-generation DBMS research prototype. While PostgreSQL retains the
powerful data model and rich data types of POSTGRES, it replaces the
PostQuel query language with an extended subset of SQL. PostgreSQL is
free and the complete source is available.
PostgreSQL, /Post-Gres-Q-L/. olarak okunur
PostgreSQL development is performed by a team of developers who all
subscribe to the PostgreSQL development mailing list. The current
coordinator is Marc G. Fournier (scrappy@PostgreSQL.org
<mailto:scrappy@PostgreSQL.org>). (See section 1.6 <#1.6> on how to
join). This team is now responsible for all development of PostgreSQL.
PostgreSQL, yeni-nesil VTYS aratrma prototipi olan POSTGRES veritaban
ynetim sisteminin gelitirilmesidir. POSTGRES' in zengin veri tiplerini
ve gl veri modelini tutarken, SQL'in gelitirilmis alt kmesi olan
PostQuel dilini kullanr. PostgreSQL cretsizdir ve kaynak kodu ak
datlr.
The authors of PostgreSQL 1.01 were Andrew Yu and Jolly Chen. Many
others have contributed to the porting, testing, debugging, and
enhancement of the code. The original Postgres code, from which
PostgreSQL is derived, was the effort of many graduate students,
undergraduate students, and staff programmers working under the
direction of Professor Michael Stonebraker at the University of
California, Berkeley.
PostgreSQL, PostgreSQL gelitirme listesine ye olan bir Internet
gelitirici takm tarafndan gelitirilir. u andaki koordinatr, Marc
G. Fournier (scrappy@PostgreSQL.org <mailto:scrappy@PostgreSQL.org>).
(Bu takma nasl katlacagnz renmek iin 1.6 <#1.6> numaral
maddeyi okuyunuz.) Bu takm, tm PostgreSQL geliiminden sorumludur.
The original name of the software at Berkeley was Postgres. When SQL
functionality was added in 1995, its name was changed to Postgres95. The
name was changed at the end of 1996 to PostgreSQL.
PostgreSQL 1.01 srmnn yazarlar Andrew Yu ve Jolly Chen idi.
Bunlarn dnda bir ka kisi de uyarlama, hata ayklama ve kodun
gelitirilmesi iin alsmt. PostgreSQL'in tredigi orijinal Postgres
kodu, lisans, lisansst ve akademisyenler tarafndan, Professor Michael
Stonebraker ) University of California, Berkeley) koordinatrlgnde
yazlmstr.
Berkley'deki yazlmn ad Postgres idi. SQL uyumluluu 1995'te
eklenince, ad Postgres 95 oldu. 1996 ylnn sonlarnda ad PostgreSQL
olarak deitirildi.
1.2) What is the copyright on PostgreSQL?
PostgreSQL is subject to the following COPYRIGHT:
1.2) PostgreSQL'in haklar nedir?
PostgreSQL Data Base Management System
......@@ -182,305 +188,302 @@ AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATIONS
TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
The above is the BSD license, the classic open-source license. It has no
restrictions on how the source code may be used. We like it and have no
intention of changing it.
stteki metin klasik ak-kod lisans olan BSD lisansdr. Kaynak kodun
nasl kullanlabileceine dair snrlamalar yoktur. Bu lisans
seviyoruz. Deitirme niyetimiz bulunmamaktadr.
1.3) What Unix platforms does PostgreSQL run on?
1.3) PostgreSQL, hangi Unix platforlarnda alsr?
In general, a modern Unix-compatible platform should be able to run
PostgreSQL. The platforms that had received explicit testing at the time
of release are listed in the installation instructions.
Genel olarak, modern bir Unix-uyumlu platform PostgreSQL'i
altracaktr. Ayrntl bilgi iin kurulum belgelerine bakabilirsiniz.
1.4) What non-Unix ports are available?
1.4) Hangi Unix olmayan uyarlamalar bulunmaktadr?
*Client*
*stemci*
It is possible to compile the /libpq/ C library, psql, and other
interfaces and client applications to run on MS Windows platforms. In
this case, the client is running on MS Windows, and communicates via
TCP/IP to a server running on one of our supported Unix platforms. A
file /win32.mak/ is included in the distribution for making a Win32
/libpq/ library and /psql/. PostgreSQL also communicates with ODBC clients.
libpq C ktphanesini, psql ve diger arabirimleri ve binary dosyalar,
MS Windows ortamlarnda alsmas iin derlemeniz mmkndr. Bu rnekte
istemcide MS Windows alsyor ve desteklenen Unix platformlarndan
birinde alsan PostgreSQL sunucuna TCP/IP ile baglanmaktadr. Datm
iindeki win31.mak dosyas ile, Win32 libpg ktphanesi ve psql
yaratabilirsiniz. PostgreSQL ayn zamanda ODBC istemcileri ile
haberlesebilmektedir.
*Server*
*Sunucu*
The database server can run on Windows NT and Win2k using Cygwin, the
Cygnus Unix/NT porting library. See /pgsql/doc/FAQ_MSWIN/ in the
distribution or the MS Windows FAQ at
http://www.PostgreSQL.org/docs/faqs/text/FAQ_MSWIN
<http://www.PostgreSQL.org/docs/faqs/text/FAQ_MSWIN>.
Veritaban sunuucsu Cygwin kullanarak Windows NT, 2K ya da XP zerinde
calistirilabilir. Dagtm iindeki pgsql/doc/FAQ_MSWN dosyasn ya da
web sitemizdeki MS Windows FAQ'u inceleyebilirsiniz.
A native port to MS Win NT/2000/XP is currently being worked on. For
more details on the current status of PostgreSQL on Windows see
http://techdocs.postgresql.org/guides/Windows
<http://techdocs.postgresql.org/guides/Windows>.
Doal Windows NT/2000/XP portu iin u anda almalar devam etmektedir.
Windows srm hakknda gncel bilgi iin,
http://techdocs.postgresql.org/guides/Windows adresini ziyaret
edebilirsiniz.
There is also a Novell Netware 6 port at http://forge.novell.com.
Ayrca, http://forge.novell.com adresinde Novell Netware 6 portu
bulunmaktadr.
1.5) Where can I get PostgreSQL?
1.5) PostgreSQL'i nereden indirebilirim?
The primary anonymous ftp site for PostgreSQL is
ftp://ftp.PostgreSQL.org/pub. For mirror sites, see our main web site.
PostgreSQL iin ana anonim ftp sitesi ftp://ftp.PostgreSQL.org/pub' dur.
Yanslar iin, ana web sayfamza bakabilirsiniz.
1.6) Where can I get support?
1.6) Nereden destek alabilirim?
The main mailing list is: pgsql-general@PostgreSQL.org
<mailto:pgsql-general@PostgreSQL.org>. It is available for discussion of
matters pertaining to PostgreSQL. To subscribe, send mail with the
following lines in the body (not the subject line):
Ana e-posta listesi : pgsql-general@PostgreSQL.org. PostgreSQL
konusundaki tartsmalara aktr. ye olmak iin, asagdaki satrlar
e-postanizin body ksmna (konu ksmna degil) yazp,
pgsql-general-request@PostgreSQL.org adresine gnderin:
subscribe
end
subscribe
end
to pgsql-general-request@PostgreSQL.org
<mailto:pgsql-general-request@PostgreSQL.org>.
Ayn zamanda, bir digest listesi bulunmaktadr. Bu listeye ye olmak
iin, pgsql-general-digest-request@PostgreSQL.org adresine, body ksmnda
There is also a digest list available. To subscribe to this list, send
email to: pgsql-general-digest-request@PostgreSQL.org
<mailto:pgsql-general-digest-request@PostgreSQL.org> with a body of:
subscribe
end
subscribe
end
yazan bir e-posta atmanz yeterli olacaktr.
Digests are sent out to members of this list whenever the main list has
received around 30k of messages.
Digest postalar, ana liste 30k civarnda e-postaya ulastiginda yelere
gnderilmektedir.
The bugs mailing list is available. To subscribe to this list, send
email to pgsql-bugs-request@PostgreSQL.org
<mailto:pgsql-bugs-request@PostgreSQL.org> with a body of:
Buglar iin bir e-posta listesi bulunmaktadr. Bu listeye ye olmak
iin, email to pgsql-bugs-request@PostgreSQL.org adresine, body ksmnda
subscribe
end
subscribe
end
There is also a developers discussion mailing list available. To
subscribe to this list, send email to
pgsql-hackers-request@PostgreSQL.org
<mailto:pgsql-hackers-request@PostgreSQL.org> with a body of:
yazan bir e-posta atmanz yeterli olacaktr.
subscribe
end
Ayn zamanda, gelistiriciler iin tartsma listesi bulunmaktadr. Bu
listeye ye olmak iin, pgsql-hackers-request@PostgreSQL.org adresine,
body ksmnda
Additional mailing lists and information about PostgreSQL can be found
via the PostgreSQL WWW home page at:
subscribe
end
http://www.PostgreSQL.org
yazan bir e-posta atmanz yeterli olacaktr.
There is also an IRC channel on EFNet and OpenProjects, channel
/#PostgreSQL/. I use the Unix command |irc -c '#PostgreSQL' "$USER"
irc.phoenix.net.|
Bunun dsndaki e-posta listelerine ve PostgreSQL hakknda bilgiye,
PostgreSQL WWW ana sayfasndan ulasabilirsiniz:
A list of commercial support companies is available at
http://www.ca.PostgreSQL.org/users-lounge/commercial-support.html.
http://www.PostgreSQL.org
Ayn zamanda, EFNet zerinde, #PostgreSQL adl bir RC kanal
bulunmaktadr. Bunun iin, irc -c '#PostgreSQL' "$USER" irc.phoenix.net
Unix komutunu kullanabilirsiniz.
1.7) What is the latest release?
Ticari destek veren firmalarn listesine
The latest release of PostgreSQL is version 7.3.3.
http://www.postgresql.org/users-lounge/commercial-support.html
We plan to have major releases every four months.
adresinden ulasabilirsiniz.
1.8) What documentation is available?
1.7) En son srm nedir?
Several manuals, manual pages, and some small test examples are included
in the distribution. See the //doc/ directory. You can also browse the
manuals online at http://www.PostgreSQL.org/docs.
PostgreSQL'in son srm 7.3.3'tr.
There are two PostgreSQL books available online at
http://www.PostgreSQL.org/docs/awbook.html and
http://www.commandprompt.com/ppbook/. There is a list of PostgreSQL
books available for purchase at http://www.ca.PostgreSQL.org/books/.
There is also a collection of PostgreSQL technical articles at
http://techdocs.PostgreSQL.org/.
Her 4 ayda major release karlmas planlanmaktadr.
/psql/ has some nice \d commands to show information about types,
operators, functions, aggregates, etc.
Our web site contains even more documentation.
1.8) Hangi belgelere ulasabilirim?
Datmn icinde, kitapciklar, kitapcik sayfalari ve bazi kk rnekler
verilmektedir. /doc dizinine baknz. Ayrica, bu el kitapklarn
online olarak http://www.PostgreSQL.org/docs/ adresinden inceleyebilirsiniz.
1.9) How do I find out about known bugs or missing features?
http://www.PostgreSQL.org/docs/awbook.html ve
http://www.commandprompt.com/ppbook adreslerinde PostgreSQL kitaplar
bulunmaktadr. PostgreSQL kitablarnn listesine,
http://www.ca.PostgreSQL.org/books/ adresinden ulaaiblirsiniz. Ayrca,
PostgreSQL konusundaki teknik makalelere de
http://techdocs.PostgreSQL.org/ adresinden ulaabilirsiniz.
PostgreSQL supports an extended subset of SQL-92. See our TODO
<http://developer.PostgreSQL.org/todo.php> list for known bugs, missing
features, and future plans.
psql'in, \d ile baslayan veri tipler, operatorler, fonksiyonlar,
aggregateler, vb. ile ilgili gzel komutlar vardr.
Web sitemiz daha fazla belgeyi iermektedir.
1.10) How can I learn SQL?
The PostgreSQL book at http://www.PostgreSQL.org/docs/awbook.html
teaches SQL. There is another PostgreSQL book at
http://www.commandprompt.com/ppbook.
<http://www.commandprompt.com/ppbook/> There is a nice tutorial at
1.9) Bilinen hatalar ya da eksik zelliklere nereden ulasabilirim?
PostgreSQL SQL-92 uyumlugugu icindedir, standartlardan fazla da
zellikleri bulunmaktadr. Bilinen hatalar, eksik zellikler ve gelecek
ile ilgili planlar iin TODO listesine baknz.
1.10) Nasl SQL renebilirim?
http:/www.PostgreSQL.org/docs/awbook.html adresindeki kitap SQL
gretecektir. http://www.commandprompt.com/ppbook adresinde de bir baska
PostgreSQL kitab bulunmaktadr.
http://www.intermedia.net/support/sql/sqltut.shtm,
<http://www.intermedia.net/support/sql/sqltut.shtm> at
http://ourworld.compuserve.com/homepages/graeme_birchall/HTM_COOK.HTM,
<http://ourworld.compuserve.com/homepages/graeme_birchall/HTM_COOK.HTM>
and at http://sqlcourse.com. <http://sqlcourse.com/>
http://ourworld.compuserve.com/homepages/graeme_birchall/HTM_COOK.HTM
http://sqlcourse.com ve http://sqlcourse2.com adreslerinde de gzel
belgeler bulunmaktadr.
Another one is "Teach Yourself SQL in 21 Days, Second Edition" at
http://members.tripod.com/er4ebus/sql/index.htm
Bir bakas da, http://members.tripod.com/er4ebus/sql/index.htm
adresinde bulunan "Teach Yourself SQL in 21 Days, Second Edition" kitabdr.
Many of our users like /The Practical SQL Handbook/, Bowman, Judith S.,
et al., Addison-Wesley. Others like /The Complete Reference SQL/, Groff
et al., McGraw-Hill.
Baz kullanclarmz da u kitab nermektedirler: The Practical SQL
Handbook, Bowman, Judith S., et al.,Addison-Wesley. Others like The
Complete Reference SQL, Groff et al., McGraw-Hill.
1.11) Is PostgreSQL Y2K compliant?
1.11) PostgreSQL 2000 ylna uyumlu mudur?
Yes, we easily handle dates past the year 2000 AD, and before 2000 BC.
Evet.
1.12) How do I join the development team?
1.12) Gelistirme takmna nasl katlabilirim?
First, download the latest source and read the PostgreSQL Developers
documentation on our web site, or in the distribution. Second, subscribe
to the /pgsql-hackers/ and /pgsql-patches/ mailing lists. Third, submit
high quality patches to pgsql-patches.
ncelikle, en son kaynak kodunu indirin ve web sitemizdeki ya da
dagtmn iindeki PostgreSQL Developer belgesini okuyun. Ardindan,
pgsql-hackers ve pgsql-patches listelerine ye olun. nc olarak da,
pgsql-pacthes listesine yksek kalitede yamalar gnderin.
There are about a dozen people who have commit privileges to the
PostgreSQL CVS archive. They each have submitted so many high-quality
patches that it was impossible for the existing committers to keep up,
and we had confidence that patches they committed were of high quality.
PostgreSQL CVS arsivine erisim izni olan, 10 kadar gelistirici
bulunmaktadir. Hepsi defalarca, diger kisilerin yaptigindan cok daha
yksek-kaliteli patchler gondermislerdir. Ayrica biz de bu
gelistiricilerin ekledikleri yamalarin yksek kalitede olduguna gveniyoruz.
1.13) How do I submit a bug report?
1.13) Bir hata raporunu nasl gnderebilirim?
Please visit the PostgreSQL BugTool page at
http://www.PostgreSQL.org/bugs/bugs.php, which gives guidelines and
directions on how to submit a bug report.
PostgreSQL BugTool sayfasina gidiniz. O sayfada bir bug bildirmek icin
neleri yapmanz gerektigi anlatilmistir.
Also check out our ftp site ftp://ftp.PostgreSQL.org/pub to see if there
is a more recent PostgreSQL version or patches.
Ayrca, ftp://ftp.PostgreSQL.org/pub ftp adresimizde, yeni bir
PostgreSQL srm ya da yamasi olup olmadigini kontrol ediniz.
1.14) How does PostgreSQL compare to other DBMSs?
1.14) PostgreSQL, diger DBMS'lerle nasl karsilastrlabilir?
There are several ways of measuring software: features, performance,
reliability, support, and price.
Bir yazilimin gcn lmek iin esitli yollar vardir: Yazilimin
zellikleri, basarm, gvenilirligi, destegi ve creti.
*Features*
PostgreSQL has most features present in large commercial DBMSs, like
transactions, subselects, triggers, views, foreign key referential
integrity, and sophisticated locking. We have some features they do
not have, like user-defined types, inheritance, rules, and
multi-version concurrency control to reduce lock contention.
zellikler:
*Performance*
PostgreSQL has performance similar to other commercial and open
source databases. it is faster for some things, slower for others.
In comparison to MySQL or leaner database systems, we are slower on
inserts/updates because of transaction overhead. Of course, MySQL
does not have any of the features mentioned in the /Features/
section above. We are built for reliability and features, though we
continue to improve performance in every release. There is an
interesting Web page comparing PostgreSQL to MySQL at
http://openacs.org/philosophy/why-not-mysql.html
<http://openacs.org/philosophy/why-not-mysql.html>
PostgreSQL mevcut byk ticari veritabanlarinin, transaction, subselect,
trigger, view, foreign key referential integrity ve sophisticated
locking gibi (user-defined types), rules, inheritance ve lock
caksmalarini dsrmek icin multi-version uyumluluk zellikleri
bulunmaktadir.
*Reliability*
We realize that a DBMS must be reliable, or it is worthless. We
strive to release well-tested, stable code that has a minimum of
bugs. Each release has at least one month of beta testing, and our
release history shows that we can provide stable, solid releases
that are ready for production use. We believe we compare favorably
to other database software in this area.
Performans (Baarm):
*Support*
Our mailing lists provide contact with a large group of developers
and users to help resolve any problems encountered. While we cannot
guarantee a fix, commercial DBMSs do not always supply a fix either.
Direct access to developers, the user community, manuals, and the
source code often make PostgreSQL support superior to other DBMSs.
There is commercial per-incident support available for those who
need it. (See FAQ section 1.6 <#1.6>.)
PostgreSQL, dier ticari ve ak kaynak kodlu veritabanlaryla yakn
baarm salar. Baz alardan daha hzldr, dier alardan da
yavatr. MySQL ya da daha zayf veritabanlar ile
karlatrldnda,insert/update islemlerinde, transaction bazl
alstmz iin daha yavaz. MySQL, yukardaki "zellikler" ksmnda
belirtilenlerden hi birine sahip deildir. Biz, baarmmz her
srmde arttrsak da, esneklik ve gelimi zellikler iin yaplanms
durumdayz . PostgreSQL'i MySQL ile karlatran u web sitesine
bakabilirsiniz: http://openacs.org/why-not-mysql.html
*Price*
We are free for all use, both commercial and non-commercial. You can
add our code to your product with no limitations, except those
outlined in our BSD-style license stated above.
Gvenilirlik:
DBMSlerin gvenilir olmas gerketigi, yoksa degerleri olmayacagini
dsnyoruz ok iyi test edilmis, dengeli alsan minimum sayda hata
ieren kod sunmaya alsyoruz. Her bir srm en az 1 aylk beta
testlerinden geirilmektedir. Srm gemiine bakarsanz, retime hazr,
dengeli ve kararl kodlar sundugumuzu grebilirsiniz. Bu alanda, diger
veritaban yaZlmlarna stnlgmz olduguna inanmaktayz
1.15) How can I financially assist PostgreSQL?
Destek:
PostgreSQL has had a first-class infrastructure since we started in
1996. This is all thanks to Marc Fournier, who has created and managed
this infrastructure over the years.
E-posta listemiz, olusan herhangi bir sorunu zebilecek byk sayda
kullanc ve gelistirici grubunu ierir. Sorununuz iin, en az bir
ticari veritaban kadar rahat zm bulabilirsiniz. Gelistiricilere,
kullanc grubuna, belgelere ve kaynak koda direk olarak erisebilme,
PostgreSQL destegini, diger DBMSlere gre daha nemli klar. Gereksinimi
olanlara, ticari destek verilebilir. (Destek iin 1.6 blmne baknz.)
Quality infrastructure is very important to an open-source project. It
prevents disruptions that can greatly delay forward movement of the project.
Fiyat:
Of course, this infrastructure is not cheap. There are a variety of
monthly and one-time expenses that are required to keep it going. If you
or your company has money it can donate to help fund this effort, please
go to http://store.pgsql.com/shopping/ and make a donation.
Ticari ve ticari olmayan tm kullanmlarnz iin PostgreSQL
cretsizdir. Kodumuzu, yukarda belirtilen BSD-stili lisanstaki
snrlamalar hari, rnnzn iine ekleyebilirsiniz.
Although the web page mentions PostgreSQL, Inc, the "contributions" item
is solely to support the PostgreSQL project and does not fund any
specific company. If you prefer, you can also send a check to the
contact address.
------------------------------------------------------------------------
1.15) PostgreSQL'e maddi adan nasl destek olabilirim?
PostgreSQL, 1996 ylndan beri 1.snf altyapya ashiptir. Bunun iin,
yllar boyu alsp bu altyapy olusturup yneten Marc Fournier'e
tesekkrler.
User Client Questions
Bir ak kaynak kodlu proje iin, kaliteli altyap ok nemlidir. Bu
altyap, projenin kesilmesini nler ve projenin ilerlemesini hzlandrr.
Tabii ki bu altyap ucuz degildir. slerin yrmesi iin eitli ylk
ve anlk harcamalarmz olmaktadr. Eger siz ya da sirketinizin bu
abamza bagsta bulunabilecek paras varsa, ltfen
http://www.pgsql.com/pg_goodies adresine gidiniz ve bagsta, hibede
bulununuz.
2.1) Are there ODBC drivers for PostgreSQL?
Web sayfasnn PostgreSQL, nc.' den bahsetmesine ragmen, "katkda
bulunanlar" (contributors) maddesi sadece PostgreSQL projesini
desteklemek iindir ve belirli bir sirketin para kaynag degildir.
isterseniz, baglant adresine bir ek gnderebilirsiniz.
------------------------------------------------------------------------
Kullanc/istemci Sorular
There are two ODBC drivers available, PsqlODBC and OpenLink ODBC.
You can download PsqlODBC from
http://gborg.postgresql.org/project/psqlodbc/projdisplay.php
<http://gborg.postgresql.org/project/psqlodbc/projdisplay.php>.
2.1) PostgreSQL icin ODBC srcleri var m?
OpenLink ODBC can be gotten from http://www.openlinksw.com
<http://www.openlinksw.com/>. It works with their standard ODBC client
software so you'll have PostgreSQL ODBC available on every client
platform they support (Win, Mac, Unix, VMS).
iki tane ODBC srcs bulunmaktadr: PsqlODBC ve OpenLink ODBC.
They will probably be selling this product to people who need
commercial-quality support, but a freeware version will always be
available. Please send questions to postgres95@openlink.co.uk
<mailto:postgres95@openlink.co.uk>.
PsqlODBC'i http://gborg.postgresql.org/project/psqlodbc/projdisplay.php
adresinden indirebilirsiniz.
OpenLink ODBC http://www.openlinksw.com adresinden alnabilir.Bu src,
kendi standart ODBC istemci yazlm ile alstndan, destekledikleri
her platformda (Win, Mac, Unix, VMS) PostgreSQL ODBC bulunmalidir.
2.2) What tools are available for using PostgreSQL with Web pages?
cretsiz srm olmakla beraber, ticari kalitede destek almak
isteyenlere satmak isteyeceklerdir. Sorularnz ltfen
postgres95@openlink.co.uk adresine gnderiniz.
A nice introduction to Database-backed Web pages can be seen at:
http://www.webreview.com
For Web integration, PHP is an excellent interface. It is at
http://www.php.net.
2.2) PostgreSQL'i web sayfalarnda kullanabilmek iin hangi
aralar bulunmaktadr?
For complex cases, many use the Perl interface and CGI.pm or mod_perl.
http://www.webreview.com adresinde, arka planda veritaban alstran
Web sayfalar iin giris seviyesinde bilgi bulunmaktadr.
Web ile btnlesme iin, PHP mkemmel bir arabirim sunar. http://www.php.net
2.3) Does PostgreSQL have a graphical user interface?
Karmak sorunlar iin, ou kisi Perl arabirimini ve CGI.pm ya da
mod_perl kullanr.
Yes, there are several graphical interfaces to PostgreSQL available.
These include PgAccess http://www.pgaccess.org
<http://www.pgaccess.org>), PgAdmin II (http://www.pgadmin.org,
Win32-only), RHDB Admin (http://sources.redhat.com/rhdb/ ) and Rekall (
http://www.thekompany.com/products/rekall/
<http://www.thekompany.com/products/rekall/>, proprietary). There is
also PHPPgAdmin ( http://phppgadmin.sourceforge.net/
<http://phppgadmin.sourceforge.net/>), a web-based interface to PostgreSQL.
See http://techdocs.postgresql.org/guides/GUITools for a more detailed list.
2.3) PostgreSQL'in grafik kullanc arabirimi var mdr?
eitli grafik arabirimlerimiz bulunmaktadr. Bunlarn arasnda,
PgAccess (http://www.pgaccess.org), PgAdmin II (http://www.pgadmin.org,
sadece Win32 iin), RHDB Admin (http://sources.redhat.com/rhdb/ ) ve
Rekall (http://www.thekompany.com/products/rekall/) bulunmaktadr.
Ayrca, PostgreSQL iin web tabanl bir arabirim olan PHPPgAdmin (
http://phppgadmin.sourceforge.net/ ) bulunmaktadr.
2.4) What languages are able to communicate with PostgreSQL?
Daha ayrntl liste iin http://techdocs.postgresql.org/guides/GUITools
adresine bakabilirsiniz.
Most popular programming languages contain an interface to PostgreSQL.
Check your programming language's list of extension modules.
The following interfaces are included in the PostgreSQL distribution:
2.4) PostgreSQL ile iletiimi kurabilmek iin hangi dilleri
kullanabilirim?
* C (libpq)
* Embedded C (ecpg)
......@@ -488,250 +491,279 @@ The following interfaces are included in the PostgreSQL distribution:
* Python (PyGreSQL)
* TCL (libpgtcl)
Additional interfaces are available at http://gborg.postgresql.org in
the /Drivers/Interfaces/ section.
Dierleri iin, http://gborg.postgresql.org adresindeki
Drivers/Interfaces blmne bakabilirsiniz.
------------------------------------------------------------------------
Administrative Questions
Ynetimsel Sorular
3.1) PostgreSQL'i, /usr/local/pgsql dizininden baska dizinlere
nasl kurabilirim?
3.1) How do I install PostgreSQL somewhere other than
//usr/local/pgsql/?
configure betigini alstrrken, --prefix seenegini veriniz.
Specify the /--prefix/ option when running /configure/.
3.2) postmaster'i baslattgmda, a Bad System Call ya da core
dumped mesaj alyorum. Neden?
3.2) When I start /postmaster/, I get a /Bad System Call/ or
core dumped message. Why?
Bunun birok nedeni olabilir. Ancak ilk kontrol edilmesi gereken sey,
ekirdeginize System V uzantlarnn kurulu olup olmadgn kontrol
etmek olabilir. PostgreSQL shared memory ve semaphores iin ekirdek
destegine gereksinim duyar.
It could be a variety of problems, but first check to see that you have
System V extensions installed in your kernel. PostgreSQL requires kernel
support for shared memory and semaphores.
3.3) postmaster'i baslattgmda, a pcMemoryCreate hatas
alyorum. Neden?
3.3) When I try to start /postmaster/, I get /IpcMemoryCreate/
errors. Why?
Ya ekirdeginizde shared memory desteginiz dzgnce
yaplandrlmamstr, ya da ekirdeginizdeki mevcut shared memory
miktarn bytmeniz gerekecektir. Gereksinim duyacagnz miktar,
mimarinize ve postmaster iin ayarladgnz tampon ile backend islemi
saysna bagldr. Tm sistemler iin, tamponlar ve islemlerde ntanml
saylarla, ~ 1MB kadar yere gereksinmeniz olacaktir.PostgreSQL
Administrator's Guide' a, shared memory ve semaphorelar hakkndaki
ayrntl bilgi iin bakabilirsiniz.
You either do not have shared memory configured properly in your kernel
or you need to enlarge the shared memory available in the kernel. The
exact amount you need depends on your architecture and how many buffers
and backend processes you configure for /postmaster/. For most systems,
with default numbers of buffers and processes, you need a minimum of ~1
MB. See the PostgreSQL Administrator's Guide
<http://www.PostgreSQL.org/docs/view.php?version=current&idoc=1&file=kernel-resources.html>
for more detailed information about shared memory and semaphores.
3.4) postmaster'i baslattgmda, a pcSemaphoreCreate hatas
alyorum. Neden?
3.4) When I try to start /postmaster/, I get
/IpcSemaphoreCreate/ errors. Why?
Eger hata, "pcSemaphoreCreate: semget failed (No space left on device)"
ise, ekirdeginiz yeterli semaphore ile yaplandrlmams demektir.
Postgres, her bir potansiyel backend iin bir semaphore gereksinmesi
duyar. Geici bir zm, postmaster backend islemleri iin daha az
miktarda snrla baslatmak olabilir. -N i varsalan deger olan 32'den
kk bir degerle baslatnz. Daha kalc bir zm, ekirdeinizin
SEMMNS ve SEMMNI parametrelerini ykseltmek olacaktr.
If the error message is /IpcSemaphoreCreate: semget failed (No space
left on device)/ then your kernel is not configured with enough
semaphores. Postgres needs one semaphore per potential backend process.
A temporary solution is to start /postmaster/ with a smaller limit on
the number of backend processes. Use /-N/ with a parameter less than the
default of 32. A more permanent solution is to increase your kernel's
SEMMNS and SEMMNI parameters.
almayan semaphorelar ar veritaban islemlerinde kme yaratabilirler.
Inoperative semaphores can also cause crashes during heavy database access.
Eger hata mesajnz baska birsey ise, ekirdeginizde semaphore destegini
yaplandrmams olabilirsiniz. Shared memory ve semaphorelar hakkndaki
daha ayrntl bilgi iin PostgreSQL Administrator's Guide'a bakabilirsiniz.
If the error message is something else, you might not have semaphore
support configured in your kernel at all. See the PostgreSQL
Administrator's Guide for more detailed information about shared memory
and semaphores.
3.5) Diger bilgisayarlarn benim PostgreSQL veritaban sunucuma
baglantlarn nasl kontrol edebilirim?
3.5) How do I control connections from other hosts?
n tanml olarak, PostgreSQL sadece yerel makineden Unix domain sockets
kullanarak baglanlmasna izin verir. Diger makineler, postmaster'a -i
etiketini geirmezseniz ve $PGDATA_pg_hba.conf dosyasn dzenleyerek
host-based authentication'a olanak vermezseniz, baglant yapamayacaklardr.
By default, PostgreSQL only allows connections from the local machine
using Unix domain sockets. Other machines will not be able to connect
unless you add the /-i/ flag to /postmaster/, *and* enable host-based
authentication by modifying the file /$PGDATA/pg_hba.conf/ accordingly.
This will allow TCP/IP connections.
3.6) Veritabani motorunu daha iyi basarim icin nasil
ayarlayabilirim?
3.6) How do I tune the database engine for better performance?
Indexler sorgular hzlandrabilir. EXPLAIN komutu, PostgreSQL'in
sorgunuzu nasl yorumladn ve hangi indexleri kullandigini grmenize
izin verir.
Certainly, indexes can speed up queries. The EXPLAIN command allows you
to see how PostgreSQL is interpreting your query, and which indexes are
being used.
Eer cok fazla INSERT islemi yapiyorsaniz, bunlar byk bir toplu islem
dosyasi kullanp COPY komutu ile veritabanina girmeyi deneyiniz. Bu,
tekil NSERTlerden daha hzldr. ikinci olarak, BEGN WORK/COMMT
transaction blogu iinde olmayan ifadeler kendi transactionlarindaymis
gibi dsnlr. oklu ifadeleri tek bir transaction blou iinde
yapabilirsiniz. Bu, transaction overheadini drecektir. Tek bir
transaction blou iinde birden ok ifadeyi altrmay
deneyebilirsiniz. Bu, transaction overhead ini drr.
If you are doing many INSERTs, consider doing them in a large batch
using the COPY command. This is much faster than individual INSERTS.
Second, statements not in a BEGIN WORK/COMMIT transaction block are
considered to be in their own transaction. Consider performing several
statements in a single transaction block. This reduces the transaction
overhead. Also, consider dropping and recreating indexes when making
large data changes.
eitli ayarlama seenekleri mevcuttur. fsync() ilemini, postmaster'
-o -F seenei ile balatarak devre d brakabilirsiniz. Bu ilem,
fsync()'lerin her transactiondan sonra diske flush etmesini engelleyecektir.
There are several tuning options. You can disable /fsync()/ by starting
/postmaster/ with a /-o -F/ option. This will prevent /fsync()/s from
flushing to disk after every transaction.
Ayn zamanda, postmaster'i -B seenei ile balatp, backend ilemleri
tarafndan kullanlan shared memorf buffers saylarn
arttrabilirsiniz. Eger bu parametreyi ok yksek tutarsanz,
ekirdeinizin shared memory blgesindeki limiti ama olaslnz
yznden postmaster balayamayabilir. Her bir tampon (buffer) 8K'dr.
ntanml say ise 64 tampondur.
You can also use the /postmaster/ /-B/ option to increase the number of
shared memory buffers used by the backend processes. If you make this
parameter too high, the /postmaster/ may not start because you have
exceeded your kernel's limit on shared memory space. Each buffer is 8K
and the default is 64 buffers.
Ayn ekilde, backend'in -S seeneini geici sralamalar iin backend
sreleri tarafndan kullanlacak hafzay arttrmak amacyla
kullanabilirsiniz. -S seenei kilobayt cinsinden deer alr ve n
tanml deeri 512'dir (512 K)
You can also use the backend /-S/ option to increase the maximum amount
of memory used by the backend process for temporary sorts. The /-S/
value is measured in kilobytes, and the default is 512 (i.e. 512K).
Tablolardaki veriyi bir indekse elemek amacyla gruplama iin CLUSTER
komutunu kullanabilirsiniz. Ayrntl bilgi iin CLUSTER komutunun
yardm sayfasna bakabilirsiniz.
You can also use the CLUSTER command to group data in tables to match an
index. See the CLUSTER manual page for more details.
3.7) Hangi hata ayklama zellikleri bulunmaktadr?
3.7) What debugging features are available?
PostgreSQL, hata ayklama amacyla kullanlabilecek durum bilgisi rapor
eden eitli zeliklere sahiptir.
PostgreSQL has several features that report status information that can
be valuable for debugging purposes.
ncelikle, configure betiini --enable-cassert seeneiyle
altrrsanz, bir ok assert() backend calmasn gzlemler ve
beklenmeyen bir durumda program durdurur.
First, by running /configure/ with the --enable-cassert option, many
/assert()/s monitor the progress of the backend and halt the program
when something unexpected occurs.
Postmaster ve postgres eitli hata ayklama seeneklerine sahiptir.
ncelikle, postmaster'i balattnzda, standart kty ve hatalar
bir log dosyasna ynlendirdiinize emin olun:
Both /postmaster/ and /postgres/ have several debug options available.
First, whenever you start /postmaster/, make sure you send the standard
output and error to a log file, like:
cd /usr/local/pgsql
./bin/postmaster >server.log 2>&1 &
Bu ilem PostgreSQL ana dizinine server.log dosyas yerletirecektir. Bu
dosya sunucunun yaad sorunlar ya da hatalar hakknda yararl
bilgiler ierir. -d seenei, hata ayklama seviyesini belirten bir
rakam ile kullanlr. Yksek hata ayklama seviyelerinin byk log
dosyalar oluturacan unutmaynz.
cd /usr/local/pgsql
./bin/postmaster >server.log 2>&1 &
Eer postmaster almyorsa, postgres backend'ini komut satrndan
altrabilir ve SQL ifadenizi direk olarak yazabilirsiniz. Bu sadece
hata ayklama amacyla nerilir. Burada, noktal virgln deil de yeni
bir satrn sorguyu sonlandrdn unutmaynz. Eer hata ayklama
sembolleri ile derlediyseniz, ne olduunu grmek iin bir hata
ayklayc kullanabilirsiniz. backend postmasterdan balatlmadndan,
edeer bir ortamda almamaktadr ve locking/backend etkileim
sorunlar artabilir.
Eer postmaster alyorsa, bir pencerede psql'i altrn ve psql
tarafndan kullanlan postgres srecinin sre numarasn (PID) bulun.
Postgres sreci ile ilikilendirmek iin bir hata ayklarc kullann.
Sorgular psql aracl ile altrabilirsiniz. Eer postgres
balangcnda hata ayklamak istiyorsanz, PGOPTIONS="-W n" seeneini
ayarlayabilir ve psql'i balatabilirsiniz. Bu ilem, balangcn n
saniye kadar gecikmesini salayacaktr; bylece hata ayklaycy srece
ilikilendirdikten sonra balang srecinin devam etmesini
salayabilirsiniz.
postgres program hata ayklama ve baarm lmleri iin -s, -A ve -t
seeneklerine sahiptir.
3.8) Baglanmaya alsken, neden "Sorry, too many clients"
hatasn alyorum?
Postmaster'in ezamanl olarak balatabilecei backend sreleri
snrlarn arttrmanz gerekmektedir.
n tanml deer 32 sretir. Bunu, postmaster'i uygun -N deeri ile ya
da postgresql.conf dosyasn dzenleyerek yeniden balatmakla
arttrabilirsiniz.
Eer -N deerini 32'den byk yapacaksanz, ayn zamanda -B deerini de
deitirmeniz gerektiini unutmayn. -B -N'nin en az 2 kat kadar
olmaldr; daha iyi baarm iin bu sayy daha da arttrmalsnz.
Yksek saydaki backend sreleri iin, eitli ekirdek yaplandrma
parametrelerini arttrmanz gerekecektir. Yaplmas gerekenler, SHMMAX,
SEMMNS, SEMMNI, NPROC, MAXUPRC ve alabilecek dosyalarn maksimum
says olan NFILE ve NINODE deerlerini kartrmaktr. Bunun nedeni,
PostgreSQL'in izin verilen backend srelerinin says zerinde bir
snr olmasdr. Bylelikle sistem kaynaklarnn dna klmayacaktr.
PostgreSQL'in 6.5 srmne kadar, en fazla backend says 64 idi ve bunu
deitirmek iin include/storage/sinvaladt.h dosyas iindeki
MaxBAckendid sabitini deitirdek sonra yazlm yeniden derlemek
gerekiyordu.
3.9) pgsql_tmp dizinin iindeki dosyalar nelerdir?
Sorgu alstrc (query executer) tarafndan yaratlan geici
dosyalardr. rnegin, bir sralama ORDER BY ile yapilacaksa ve sralama
backend'in -s parametresinin izin verdiginden daha fazla alana
gereksinim duyuyorsa, ekstra veriyi tutmak iin geici dosyalar yaratlr.
Geici dosyalar, eger sralama srasnda backend gmezse otomatik
olarak silinecektir. Eger alsan durumda bir backendiniz yoksa,
pg_tempNNN.NN dosyalarn silmeniz gvenlidir..
3.10) PostgreSQL srmlerini ykselmek iin neden bir
dump/reload ilemi gerekletirmek zorundaym?
PostgreSQL takm ara srmlerde sadece kk deiiklikler yapmaktadr;
bu yzden 7.2 srmnden 7.2.1'e ykseltmek dump/restore ilemi
gerekmemektedir. Ancak, esas srmlerde (rnek: 7.2'den 7.3'e)
ounlukla sistem tablolarnn ve veri dosyalarnn i yaps
deitirilir. Bu deiiklikler ounlukla karmaktr; dolaysyla veri
dosyalarnn geriye dnk uyumluluu ilemlerini yapmyoruz. Dump
ilemi, veriyi genel biimde alacandan yeniden ykleme esnasnda veri,
yeni i biime uygun ekilde yerletirilecektir.
This will put a server.log file in the top-level PostgreSQL directory.
This file contains useful information about problems or errors
encountered by the server. /Postmaster/ has a /-d/ option that allows
even more detailed information to be reported. The /-d/ option takes a
number that specifies the debug level. Be warned that high debug level
values generate large log files.
Disk biiminin deimedii srmlerde, pg_upgrade betii gncellemenin
bir dump/restore gerektirmeden yaplmasn salayacaktr. pg_upgrade
betiinin o srm iin bulunup bulunmadn srm notlar iinde
bulabilirsiniz.
If /postmaster/ is not running, you can actually run the /postgres/
backend from the command line, and type your SQL statement directly.
This is recommended *only* for debugging purposes. Note that a newline
terminates the query, not a semicolon. If you have compiled with
debugging symbols, you can use a debugger to see what is happening.
Because the backend was not started from /postmaster/, it is not running
in an identical environment and locking/backend interaction problems may
not be duplicated.
If /postmaster/ is running, start /psql/ in one window, then find the
PID of the /postgres/ process used by /psql/. Use a debugger to attach
to the /postgres/ PID. You can set breakpoints in the debugger and issue
queries from /psql/. If you are debugging /postgres/ startup, you can
set PGOPTIONS="-W n", then start /psql/. This will cause startup to
delay for /n/ seconds so you can attach to the process with the
debugger, set any breakpoints, and continue through the startup sequence.
------------------------------------------------------------------------
The /postgres/ program has /-s, -A/, and /-t/ options that can be very
useful for debugging and performance measurements.
You can also compile with profiling to see what functions are taking
execution time. The backend profile files will be deposited in the
/pgsql/data/base/dbname/ directory. The client profile file will be put
in the client's current directory. Linux requires a compile with
/-DLINUX_PROFILE/ for proper profiling.
letimsel Sorular
3.8) Why do I get /"Sorry, too many clients"/ when trying to
connect?
4.1) Binary cursor ve normal cursor arasindaki fark nedir?
You need to increase /postmaster/'s limit on how many concurrent backend
processes it can start.
DECLARE yardm sayfasina bakiniz.
The default limit is 32 processes. You can increase it by restarting
/postmaster/ with a suitable /-N/ value or modifying /postgresql.conf/.
Note that if you make /-N/ larger than 32, you must also increase /-B/
beyond its default of 64; /-B/ must be at least twice /-N/, and probably
should be more than that for best performance. For large numbers of
backend processes, you are also likely to find that you need to increase
various Unix kernel configuration parameters. Things to check include
the maximum size of shared memory blocks, SHMMAX; the maximum number of
semaphores, SEMMNS and SEMMNI; the maximum number of processes, NPROC;
the maximum number of processes per user, MAXUPRC; and the maximum
number of open files, NFILE and NINODE. The reason that PostgreSQL has a
limit on the number of allowed backend processes is so your system won't
run out of resources.
3.9) What is in the /pgsql_tmp/ directory?
This directory contains temporary files generated by the query executor.
For example, if a sort needs to be done to satisfy an ORDER BY and the
sort requires more space than the backend's /-S/ parameter allows, then
temporary files are created here to hold the extra data.
The temporary files are usually deleted automatically, but might remain
if a backend crashes during a sort. A stop and restart of the
/postmaster/ will remove files from those directories.
3.10) Why do I need to do a dump and restore to upgrade between
major PostgreSQL releases?
The PostgreSQL team makes only small changes between minor releases, so
upgrading from 7.2 to 7.2.1 does not require a dump and restore.
However, major releases (e.g. from 7.2 to 7.3) often change the internal
format of system tables and data files. These changes are often complex,
so we don't maintain backward compatability for data files. A dump
outputs data in a generic format that can then be loaded in using the
new internal format.
4.2) Sorgunun sadece ilk birka satrn nasil SELECT edebilirim?
In releases where the on-disk format does not change, the /pg_upgrade/
script can be used to upgrade without a dump/restore. The release notes
mention whether /pg_upgrade/ is available for the release.
FETCH yardm sayfasina bakiniz, aya da SELECT ... LIMIT.... kullannz.
------------------------------------------------------------------------
The entire query may have to be evaluated, even if you only want the
first few rows. Consider a query that has an ORDER BY. f there is an
index that matches the ORDER BY, PostgreSQL may be able to evaluate only
the first few records requested, or the entire query may have to be
evaluated until the desired rows have been generated.
Operational Questions
4.3) psql'in iinde grdgm tablolarin ya da diger seylerin
listesini nasil alabilirim?
pgsql/src/bin/psql/describe.c iindeki psql kaynak kodunu
okuyabilirsiniz. Bu kod, psql'in \ ile baslayan komutlarnn ktsn
olusturan SQL komutlarini ierir. Ayn zamanda, psql'i -E seenei ile
balatp, verdiiniz komutlar altrmak iin yapt sorgularn
ktlarn grebilirsiniz.
4.1) What is the difference between binary cursors and normal
cursors?
See the DECLARE manual page for a description.
4.4) Bir tablodan bir kolonu nasl kaldrabilirim?
Bu zellik (ALTER TABLE DROP COLUMN) 7.3 srm ile gelmitir. Eski
srmlerde aadakileri uygulamalsnz:
4.2) How do I SELECT only the first few rows of a query?
BEGIN;
LOCK TABLE old_table;
SELECT ... -- select all columns but the one you want to remove
INTO TABLE new_table
FROM old_table;
DROP TABLE old_table;
ALTER TABLE new_table RENAME TO old_table;
COMMIT;
See the FETCH manual page, or use SELECT ... LIMIT....
The entire query may have to be evaluated, even if you only want the
first few rows. Consider using a query that has an ORDER BY. If there is
an index that matches the ORDER BY, PostgreSQL may be able to evaluate
only the first few records requested, or the entire query may have to be
evaluated until the desired rows have been generated.
4.5) Bir satr, tablo ve veritaban icin en fazla byklk nedir?
4.3) How do I get a list of tables or other things I can see in
/psql/?
Snrlar:
You can read the source code for /psql/ in file
/pgsql/src/bin/psql/describe.c/. It contains SQL commands that generate
the output for psql's backslash commands. You can also start /psql/ with
the /-E/ option so it will print out the queries it uses to execute the
commands you give.
Veritabani icin en fazla byklk nedir?
Snrsz (4 TB'lk veritaban bulunmaktadr)
Bir tablo icin en fazla byklk nedir?
16 TB
4.4) How do you remove a column from a table?
Bir satr iin en fazla byklk nedir?
1.6 TB
This functionality was added in release 7.3 with ALTER TABLE DROP
COLUMN. In earlier versions, you can do this:
Bir alan iin en fazla byklk nedir?
1 GB
BEGIN;
LOCK TABLE old_table;
SELECT ... -- select all columns but the one you want to remove
INTO TABLE new_table
FROM old_table;
DROP TABLE old_table;
ALTER TABLE new_table RENAME TO old_table;
COMMIT;
Tabloda en fazla satr says katr?
Snrsz
Bir tabloda olabilecek en fazla kolon says katr?
Kolon tiplerine bal olarak 250-1600
4.5) What is the maximum size for a row, a table, and a database?
Bir tabloda olabilecek en fazla index says katr?
snrsz
These are the limits:
......@@ -1201,9 +1233,10 @@ There are several master/slave replication options available. These
allow only the master to make database changes and the slave can only do
database reads. The bottom of
http://gborg.PostgreSQL.org/genpage?replication_research
<http://gborg.PostgreSQL.org/genpage?replication_research> lists them. A
<http://gborg.postgresql.org/genpage?replication_research> lists them. A
multi-master replication solution is being worked on at
http://gborg.PostgreSQL.org/project/pgreplication/projdisplay.php.
http://gborg.PostgreSQL.org/project/pgreplication/projdisplay.php
<http://gborg.postgresql.org/project/pgreplication/projdisplay.php>.
4.28) What encryption options are available?
......@@ -1237,19 +1270,20 @@ Send your extensions to the /pgsql-hackers/ mailing list, and they will
eventually end up in the /contrib// subdirectory.
5.3) How do I write a C function to return a tuple?
5.3) Bir tuple dndrmek iin bir C fonksiyonunu nasl yazarm?
In versions of PostgreSQL beginning with 7.3, table-returning functions
are fully supported in C, PL/PgSQL, and SQL. See the Programmer's Guide
for more information. An example of a table-returning function defined
in C can be found in /contrib/tablefunc/.
PostgreSQL 7.3 srm ile birlikte, C, PL/PgSQL ve SQL kullanlarak
tablo-dndren fonksiyonlar tamamen desteklenmektedir. Ayrntl bilgi
iin "Programmer's Guide" a bakabilrisiniz. Bir rnei
/contrib/tablefunc/ iinde bulabilirsiniz.
5.4) I have changed a source file. Why does the recompile not
see the change?
5.4) Bir kaynak dosyasnda deiiklik yaptm. Yeniden derlememe
ramen deiiklik geerli olmuyor. Neden?
The /Makefiles/ do not have the proper dependencies for include files.
You have to do a /make clean/ and then another /make/. If you are using
GCC you can use the /--enable-depend/ option of /configure/ to have the
compiler compute the dependencies automatically.
/Makefile'lar/ include dosyalar iin tam bir bamllk iermezler.
ncelikle /make clean/, ardndan da baska bir /make/ ilemi yapmanz
gerekir. GCC kullanyorsaniz, /configure/ betiinin /--enable-depend/
seeneini, derleyicinin bamllklar otomatik olarak hesaplamas iin
kullanabilirsiniz.
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