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Commit 2ffba0d4 authored by Bruce Momjian's avatar Bruce Momjian
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Changes to get ready for 6.0 final release.

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HISTORY
View file @ 2ffba0d4
PostgreSQL 6.0 beta Thu Dec 26 16:47:43 EST 1996 PostgreSQL 6.0 Wed Jan 29 00:19:54 EST 1997
------------------------------------------------------------- -------------------------------------------------------------
A dump/restore is required for those wishing to migrate data from A dump/restore is required for those wishing to migrate data from
...@@ -68,6 +68,7 @@ Allow restriction on who can do backend COPY(Bryan) ...@@ -68,6 +68,7 @@ Allow restriction on who can do backend COPY(Bryan)
Can shrink tables, pg_time and pg_log(Vadim & Erich) Can shrink tables, pg_time and pg_log(Vadim & Erich)
Change debug level 2 to print queries only, changed debug heading layout(Bruce) Change debug level 2 to print queries only, changed debug heading layout(Bruce)
Change default decimal constant representation from float4 to float8(Bruce) Change default decimal constant representation from float4 to float8(Bruce)
European date format now set when postmaster is started
Execute lowercase function names if not found with exact case Execute lowercase function names if not found with exact case
Fixes for aggregate/GROUP processing, allow 'select sum(func(x),sum(x+y) from z' Fixes for aggregate/GROUP processing, allow 'select sum(func(x),sum(x+y) from z'
Gist now included in the distrubution(Marc) Gist now included in the distrubution(Marc)
...@@ -79,7 +80,7 @@ Libpq++ improvements ...@@ -79,7 +80,7 @@ Libpq++ improvements
New options to initdb(Bryan) New options to initdb(Bryan)
Pg_dump allow dump of oid's(Bruce) Pg_dump allow dump of oid's(Bruce)
Pg_dump create indexes after tables are loaded for speed(Bruce) Pg_dump create indexes after tables are loaded for speed(Bruce)
Pg_dump(Bruce) Pg_dumpall dumps all databases, and the user table
Pginterface additions for NULL values(Bruce) Pginterface additions for NULL values(Bruce)
Prevent postmaster from being run as root Prevent postmaster from being run as root
Psql \h and \? is now readable(Bruce) Psql \h and \? is now readable(Bruce)
...@@ -94,6 +95,7 @@ Remove compile-time parameters to enable binary distributions(Bryan) ...@@ -94,6 +95,7 @@ Remove compile-time parameters to enable binary distributions(Bryan)
Reverse meaning of HBA masks(Bryan) Reverse meaning of HBA masks(Bryan)
Secure Authentication of local users(Bryan) Secure Authentication of local users(Bryan)
Speed up vacuum(Vadim) Speed up vacuum(Vadim)
Vacuum now had VERBOSE option(Bruce)
Source tree changes Source tree changes
------------------- -------------------
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doc/FAQ
View file @ 2ffba0d4
Frequently Asked Questions (FAQ) for PostgreSQL
Last updated: Tue Jan 28 20:08:25 EST 1997
Version: 6.0
Current maintainer: Bruce Momjian (maillist@candle.pha.pa.us)
The most recent version of this document can be viewed at the postgreSQL Web
site, http://postgreSQL.org.
Linux-specific questions are answered in
http://postgreSQL.org/docs/FAQ-Linux.phtml.
Irix-specific questions are answered in
http://postgreSQL.org/docs/FAQ-Irix.phtml.
Changes in this version (* = modified, + = new):
* *1.1) What is PostgreSQL?
* *1.5) Support for PostgreSQL
* *1.6) Latest release of PostgreSQL
* *1.10 Does PostgreSQL work with databases from earlier versions of
postgres?
* *3.1) How do I specify a KEY or other constraints on a column?
* *3.3) How do I define a unique indices?
* *3.11) Why doesn't the != operator work?
* *3.26) Why are my table files not getting any smaller after a delete?
* *3.28) I get the error 'default index class unsupported' when creating
an index. How do I do it?
* *3.37) What is the time-warp feature and how does it relate to vacuum?
* *5.1) How do I make a bug report?
----------------------------------------------------------------------------
html>
FREQUENTLY ASKED QUESTIONS (FAQ) FOR POSTGRESQL
Last updated: Thu Dec 12 21:30:37 EST 1996
Version: 6.0
Current maintainer: Bruce Momjian (maillist@candle.pha.pa.us)
The most recent version of this document can be viewed at the
postgreSQL Web site, http://postgreSQL.org.
Linux-specific questions are answered in
http://postgreSQL.org/docs/FAQ-Linux.phtml.
Irix-specific questions are answered in
http://postgreSQL.org/docs/FAQ-Irix.phtml.
Changes in this version (* = modified, + = new):
*1.1) What is PostgreSQL?
*1.5) Support for PostgreSQL
*1.6) Latest release of PostgreSQL
*1.10 Does PostgreSQL work with databases from earlier versions of
postgres?
*3.1) How do I specify a KEY or other constraints on a column?
*3.3) How do I define a unique indices?
*3.11) Why doesn't the != operator work?
*3.26) Why are my table files not getting any smaller after a delete?
*3.28) I get the error 'default index class unsupported' when creating
an index. How do I do it?
*3.37) What is the time-warp feature and how does it relate to vacuum?
*5.1) How do I make a bug report?
_________________________________________________________________
Questions answered: Questions answered:
1) General questions 1) General questions
1.1) What is PostgreSQL? 1.1) What is PostgreSQL?
1.2) What does PostgreSQL run on? 1.2) What does PostgreSQL run on?
1.3) Where can I get PostgreSQL? 1.3) Where can I get PostgreSQL?
1.4) What's the copyright on PostgreSQL? 1.4) What's the copyright on PostgreSQL?
1.5) Support for PostgreSQL 1.5) Support for PostgreSQL
1.6) Latest release of PostgreSQL 1.6) Latest release of PostgreSQL
1.7) Is there a commercial version of PostgreSQL? 1.7) Is there a commercial version of PostgreSQL?
1.9) What version of SQL does PostgreSQL use? 1.9) What version of SQL does PostgreSQL use?
1.10) Does PostgreSQL work with databases from earlier versions of 1.10) Does PostgreSQL work with databases from earlier versions of postgres?
postgres? 1.11) How many people use PostgreSQL?
1.11) How many people use PostgreSQL?
2) Installation questions
2) Installation questions
2.1) initdb doesn't run
2.1) initdb doesn't run 2.2) when I start up the postmaster, I get "FindBackend: could not find a
2.2) when I start up the postmaster, I get "FindBackend: could not backend to execute..." "postmaster: could not find backend to execute..."
find a backend to execute..." "postmaster: could not find backend to 2.3) The system seems to be confused about commas, decimal points, and date
execute..." formats.
2.3) The system seems to be confused about commas, decimal points, and 2.4) How do I install PostgreSQL somewhere other than /usr/local/pgsql?
date formats. 2.5) When I run postmaster, I get a Bad System Call core dumped message.
2.4) How do I install PostgreSQL somewhere other than 2.6) When I try to start the postmaster, I get IpcMemoryCreate errors.
/usr/local/pgsql? 2.7) I have changed a source file, but a recompile does not see the change.
2.5) The backend compiled successfully, but compiling libpq resulted 2.8) I have changed a source file, but a recompile does not see the change?
in a complaint: "libpq/pqcomm.h" not found when compiling fe-auth.c. 3.1) How do I specify a KEY or other constraints on a column?
2.6) When I run postmaster, I get a Bad System Call core dumped 3.2) Does PostgreSQL support nested subqueries?
message. 3.3) How do I define a unique indices?
2.7) When I try to start the postmaster, I get IpcMemoryCreate errors. 3.4) I've having a lot of problems using rules.
2.8) I have changed a source file, but a recompile does not see the 3.5) I can't seem to write into the middle of large objects reliably.
change. 3.6) Does PostgreSQL have a graphical user interface? A report generator? A
embedded query language interface?
3) PostgreSQL Features questions 3.7) How can I write client applications to PostgreSQL?
3.8) How do I prevent other hosts from accessing my PostgreSQL
3.1) How do I specify a KEY or other constraints on a column? 3.9) How do I set up a pg_group?
3.2) Does PostgreSQL support nested subqueries? 3.10) What is the exact difference between binary cursors and normal
3.3) How do I define a unique indices? cursors?
3.4) I've having a lot of problems using rules. 3.11) Why doesn't the != operator work?
3.5) I can't seem to write into the middle of large objects reliably. 3.12) What is a R-tree index and what is it used for?
3.6) Does PostgreSQL have a graphical user interface? A report 3.13) What is the maximum size for a tuple?
generator? A embedded query language interface? 3.14) I defined indices but my queries don't seem to make use of them. Why?
3.7) How can I write client applications to PostgreSQL? 3.15) Are there ODBC drivers for PostgreSQL?
3.8) How do I prevent other hosts from accessing my PostgreSQL 3.16) How do I use postgres for multi-dimensional indexing (> 2 dimensions)?
3.9) How do I set up a pg_group? 3.17) How do I do regular expression searches? case-insensitive regexp
3.10) What is the exact difference between binary cursors and normal searching?
cursors? 3.18) I can't access the database as the 'root' user.
3.11) Why doesn't the != operator work? 3.19) I experienced a server crash during a vacuum. How do I remove the lock
3.12) What is a R-tree index and what is it used for? file?
3.13) What is the maximum size for a tuple? 3.20) What is the difference between the various character types?
3.14) I defined indices but my queries don't seem to make use of them. 3.21) In a query, how do I detect if a field is NULL?
Why? 3.22) How do I see how the query optimizer is evaluating my query?
3.15) Are there ODBC drivers for PostgreSQL? 3.23) How do I create a serial field?
3.16) How do I use postgres for multi-dimensional indexing (> 2 3.24) How do I create a multi-column index?
dimensions)? 3.25) What are the temp_XXX files in my database directory?
3.17) How do I do regular expression searches? case-insensitive regexp 3.26) Why are my table files not getting any smaller after a delete?
searching? 3.27) Why can't I connect to my database from another machine?
3.18) I can't access the database as the 'root' user. 3.28) I get the error 'default index class unsupported' when creating an
3.19) I experienced a server crash during a vacuum. How do I remove index. How do I do it?
the lock file? 3.29) Why does creating an index crash the backend server?
3.20) What is the difference between the various character types? 3.30) How do I specify a decimal constant as a float8, or a string as a
3.21) In a query, how do I detect if a field is NULL? text? Why am I getting poor precision?
3.22) How do I see how the query optimizer is evaluating my query? 3.31) How do I find out what indexes or operations are defined in the
3.23) How do I create a serial field? database?
3.24) How do I create a multi-column index? 3.32) My database is corrupt. I can't do anything. What should I do?
3.25) What are the temp_XXX files in my database directory? 3.33) Createdb, destroydb, createuser, destroyuser don't run. Why?
3.26) Why are my table files not getting any smaller after a delete? 3.34) Why does 'createuser' return 'unexpected last match in input()'?
3.27) Why can't I connect to my database from another machine? 3.35) All my servers crash under concurrent table access. Why?
3.28) I get the error 'default index class unsupported' when creating 3.36) What tools are available for hooking postgres to Web pages?
an index. How do I do it? 3.37) What is the time-warp feature and how does it relate to vacuum?
3.29) Why does creating an index crash the backend server? 3.38) How do I tune the database engine for better performance?
3.30) How do I specify a decimal constant as a float8, or a string as 3.39) What debugging features are available in PostgreSQL?
a text? Why am I getting poor precision? 3.40) What is an oid? What is a tid?
3.31) How do I find out what indexes or operations are defined in the 3.41) What is the meaning of some of the terms used in Postgres?
database?
3.32) My database is corrupt. I can't do anything. What should I do? 4) Questions about extending PostgreSQL
3.33) Createdb, destroydb, createuser, destroyuser don't run. Why?
3.34) Why does 'createuser' return 'unexpected last match in input()'? 4.1) I wrote a user-defined function and when I run it in psql, it dumps
3.35) All my servers crash under concurrent table access. Why? core.
3.36) What tools are available for hooking postgres to Web pages? 4.2) I get messages of the type NOTICE:PortalHeapMemoryFree: 0x402251d0
3.37) What is the time-warp feature and how does it relate to vacuum? 4.3) I've written some nifty new types and functions for PostgreSQL.
3.38) How do I tune the database engine for better performance? 4.4) How do I write a C function to return a tuple?
3.39) What debugging features are available in PostgreSQL?
3.40) What is an oid? What is a tid? 5) Bugs
3.41) What is the meaning of some of the terms used in Postgres?
5.1) How do I make a bug report?
4) Questions about extending PostgreSQL ----------------------------------------------------------------------------
4.1) I wrote a user-defined function and when I run it in psql, it
dumps core.
4.2) I get messages of the type NOTICE:PortalHeapMemoryFree:
0x402251d0
4.3) I've written some nifty new types and functions for PostgreSQL.
4.4) How do I write a C function to return a tuple?
5) Bugs
5.1) How do I make a bug report?
_________________________________________________________________
Section 1: General Questions Section 1: General Questions
1.1) What is PostgreSQL? 1.1) What is PostgreSQL?
PostgreSQL is an enhancement of the POSTGRES database management system, a
next-generation DBMS research prototype. While PostgreSQL retains the
PostgreSQL is an enhancement of the POSTGRES database management powerful data model and rich data types of POSTGRES, it replaces the
system, a next-generation DBMS research prototype. While PostgreSQL PostQuel query language with an extended subset of SQL. PostgreSQL is free
retains the powerful data model and rich data types of POSTGRES, it and the complete source is available.
replaces the PostQuel query language with an extended subset of SQL.
PostgreSQL is free and the complete source is available. PostgreSQL development is being performed by a team of Internet developers
who all subscribe to the PostgreSQL development mailing list. The current
PostgreSQL development is being performed by a team of Internet coordinator is Marc G. Fournier (scrappy@postgreSQL.org). (See below on how
developers who all subscribe to the PostgreSQL development mailing to join). This team is now responsible for all current and future
list. The current coordinator is Marc G. Fournier development of PostgreSQL.
(scrappy@postgreSQL.org). (See below on how to join). This team is
now responsible for all current and future 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
The authors of PostgreSQL 1.01 were Andrew Yu and Jolly Chen. Many code. The original Postgres code, from which PostgreSQL is derived, was the
others have contributed to the porting, testing, debugging and effort of many graduate students, undergraduate students, and staff
enhancement of the code. The original Postgres code, from which programmers working under the direction of Professor Michael Stonebraker at
PostgreSQL is derived, was the effort of many graduate students, the University of California, Berkeley.
undergraduate students, and staff programmers working under the
direction of Professor Michael Stonebraker at the University of The original name of the software at Berkeley was Postgres. When SQL
California, Berkeley. functionality was added in 1995, its name was changed to Postgres95. The
name was changed at the end of 1996 to PostgreSQL.
The original name of the software at Berkeley was Postgres. When SQL
functionality was added in 1995, its name was changed to Postgres95. 1.2) What does PostgreSQL run on?
The name was changed at the end of 1996 to PostgreSQL.
The authors have compiled and tested PostgreSQL on the following
1.2) What does PostgreSQL run on? platforms(some of these compiles require gcc 2.7.0):
* aix - IBM on AIX 3.2.5
* alpha - DEC Alpha AXP on OSF/1 2.0
The authors have compiled and tested PostgreSQL on the following * BSD44_derived - OSs derived from 4.4-lite BSD (NetBSD, FreeBSD)
platforms(some of these compiles require gcc 2.7.0): * bsdi - BSD/OS 2.0, 2.01, 2.1
* DEC Alpha AXP on OSF/1 2.0 * dgux - DG/UX 5.4R3.10
* HP PA-RISC on HP-UX 9.0 * hpux - HP PA-RISC on HP-UX 9.0
* i386 Solaris * i386_solaris - i386 Solaris
* SUN SPARC on Solaris 2.4 * irix5 - SGI MIPS on IRIX 5.3
* SUN SPARC on SunOS 4.1.3 * linux - Intel x86 on Linux 1.2 and Linux ELF (For non-ELF Linux, see
* DEC MIPS on Ultrix 4.4 LINUX_ELF below).
* Intel x86 on Linux 1.2 and Linux ELF * next - Motorola MC68K or Intel x86 on NeXTSTEP 3.2
* OSs derived from 4.4-lite BSD (NetBSD, FreeBSD) * sparc_solaris - SUN SPARC on Solaris 2.4
* IBM on AIX 3.2.5 * sunos4 - SUN SPARC on SunOS 4.1.3
* BSD/OS 2.0, 2.01 & 2.1 * svr4 - Intel x86 on Intel SVR4
* SGI MIPS on IRIX 5.3 * ultrix4 - DEC MIPS on Ultrix 4.4
1.3) Where can I get PostgreSQL?
The following ports are bundled with the PostgreSQL distribution. The The primary anonymous ftp site for PostgreSQL is:
authors do not have handy access to these platforms but the ports have
been tested by the others. * ftp://ftp.postgreSQL.org/pub
* Motorola MC68K or Intel x86 on NeXTSTEP 3.2
* Intel x86 on Intel SVR4 A mirror site exists at:
* ftp://postgres95.vnet.net/pub/postgres95
* ftp://ftp.luga.or.at/pub/postgres95
1.3) Where can I get PostgreSQL? * ftp://cal011111.student.utwente.nl/pub/postgres95
* ftp://ftp.uni-trier.de/pub/database/rdbms/postgres/postgres95
* ftp://rocker.sch.bme.hu
The primary anonymous ftp site for PostgreSQL is: 1.4) What's the copyright on PostgreSQL?
* ftp://ftp.postgreSQL.org/pub
PostgreSQL is subject to the following COPYRIGHT.
PostgreSQL Data Base Management System
A mirror site exists at:
* ftp://postgres95.vnet.net/pub/postgres95 Copyright (c) 1994-6 Regents of the University of California
* ftp://ftp.luga.or.at/pub/postgres95
* ftp://cal011111.student.utwente.nl/pub/postgres95 Permission to use, copy, modify, and distribute this software and its
* ftp://ftp.uni-trier.de/pub/database/rdbms/postgres/postgres95 documentation for any purpose, without fee, and without a written agreement
* ftp://rocker.sch.bme.hu is hereby granted, provided that the above copyright notice and this
paragraph and the following two paragraphs appear in all copies.
1.4) What's the copyright on PostgreSQL?
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,
PostgreSQL is subject to the following COPYRIGHT. EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.
PostgreSQL Data Base Management System
THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
Copyright (c) 1994-6 Regents of the University of California INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN
Permission to use, copy, modify, and distribute this software and its "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATIONS TO
documentation for any purpose, without fee, and without a written PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
agreement is hereby granted, provided that the above copyright notice
and this paragraph and the following two paragraphs appear in all 1.5) Support for PostgreSQL
copies.
There is no official support for PostgreSQL from the original maintainers or
IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY from University of California, Berkeley. It is maintained through volunteer
FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, effort only.
INCLUDING LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND
ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN The main mailing list is: questions@postgreSQL.org. It is available for
ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. discussion o f matters pertaining to PostgreSQL, including but not limited
to bug reports and fixes. For info on how to subscribe, send a mail with the
THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES, lines in the body (not the subject line)
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE subscribe
PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE UNIVERSITY OF end
CALIFORNIA HAS NO OBLIGATIONS TO PROVIDE MAINTENANCE, SUPPORT,
UPDATES, ENHANCEMENTS, OR MODIFICATIONS. to questions-request@postgreSQL.org.
1.5) Support for PostgreSQL There is also a digest list available. To subscribe to this list, send email
to: questions-digest-request@postgreSQL.org with a BODY of:
subscribe
There is no official support for PostgreSQL from the original end
maintainers or from University of California, Berkeley. It is
maintained through volunteer effort only. Digests are sent out to members of this list whenever the main list has
received around 30k of messages.
The main mailing list is: questions@postgreSQL.org. It is available
for discussion o f matters pertaining to PostgreSQL, including but not There is a bugs mailing list available. To subscribe to this list, send
limited to bug reports and fixes. For info on how to subscribe, send a email to bugs-request@postgreSQL.org with a BODY of:
mail with the lines in the body (not the subject line)
There is also a developers discussion mailing list available. To subscribe
to this list, send email to hackers-request@postgreSQL.org with a BODY of:
help
info questions subscribe
end
Additional information about PostgreSQL can be found via the PostgreSQL WWW
to majordomo@postgreSQL.org. home page at:
There is also a digest list available. To subscribe to this list, send
email to: majordomo@postgreSQL.org with a BODY of:
subscribe questions-digest
Digests are sent out to members of this list whenever the main list
has received around 30k of messages.
There is also a developers mailing list available. To subscribe to
this list, send email to hackers-request@postgreSQL.org with a BODY
of:
subscribe hackers
Additional information about PostgreSQL can be found via the
PostgreSQL WWW home page at:
http://postgreSQL.org http://postgreSQL.org
1.6) Latest release of PostgreSQL
The latest release of PostgreSQL is version 1.09. The next release
will be numbered 6.0 for historical reasons. This release is in beta
and is available at our ftp site. We expect the beta period to be
complete during the week of January 2, 1997. For information about
what is new in 6.0, see our TODO list on our WWW page.
We expect a 7.0 release in several months that will remove time-travel
and reduce by 50% the size of on-disk system columns maintained for
each row in a table. This release will also require a dump and
restore.
1.7) Is there a commercial version of PostgreSQL?
Illustra Information Technology (a wholly owned subsidiary of Informix
Software, Inc.) sells an object-relational DBMS called Illustra that
was originally based on postgres. Illustra has cosmetic similarities
to PostgreSQL but has more features, is more robust, performs better,
and offers real documentation and support. On the flip side, it costs
money. For more information, contact sales@illustra.com
1.8) What documentation is available for PostgreSQL?
A user manual, manual pages, and some small test examples are included
in the distribution. The sql and built-in manual pages are
particularly important.
The www page contains pointers to an implementation guide and five
papers written about postgres design concepts and features.
1.9) What version of SQL does PostgreSQL use?
PostgreSQL supports a subset of SQL-92. It has most of the important
constructs but lacks some of the functionality. The most visible
differences are:
* no support for nested subqueries
* no HAVING clause under a GROUP BY
On the other hand, you get to create user-defined types, functions,
inheritance etc. If you're willing to help with PostgreSQL coding,
eventually we can also add the missing features listed above.
1.10) Does PostgreSQL work with databases from earlier versions of postgres?
PostgreSQL v1.09 is compatible with databases created with v1.01.
Those upgrading from 1.0 should read the directions in the
MIGRATION_1.0_TO_1.02 directory.
Upgrading to 6.0 requires a dump and restore.
1.11) How many people use PostgreSQL?
Since we don't have any licensing or registration scheme, it's
impossible to tell. We do know hundreds copies of PostgreSQL v1.* have
been downloaded, and that there many hundreds of subscribers to the
mailing lists.
_________________________________________________________________
Section 2: Installation Questions
2.1) initdb doesn't run
* check to see that you have the proper paths set
* check that the 'postgres' user owns all the right files
* ensure that there are files in $PGDATA/files, and that they are
non-empty. If they aren't, then "gmake install" failed for some
reason
2.2) when I start up the postmaster, I get "FindBackend: could not find a
backend to execute..." "postmaster: could not find backend to execute..."
You probably do not have the right path set up. The 'postgres'
executable needs to be in your path.
2.3) The system seems to be confused about commas, decimal points, and date
formats.
Check your locale configuration. PostgreSQL uses the locale settings
of the user that ran the postmaster process. Set those accordingly for
your operating environment.
2.4) How do I install PostgreSQL somewhere other than /usr/local/pgsql?
You need to manually edit the paths in src/Makefile.global to your
site configuration.
2.5) The backend compiled successfully, but compiling libpq resulted in a
complaint: "libpq/pqcomm.h" not found when compiling fe-auth.c.
You've probably installed PostgreSQL somewhere other than
/usr/local/pgsql, but didn't edit the src/Makefile.global accordingly.
See question 2.6.
2.6) When I run postmaster, I get a Bad System Call core dumped message.
It could be a variety of problems, but first check to see that you
have system V extensions installed on your kernel. PostgreSQL requires
kernel support for shared memory.
2.7) I get the error message "obj/fmgr.h: No such file or directory"
This indicates that you did not generate the file fmgr.h properly.
Something failed in the running of the
src/backend/utils/Gen_fmgrtab.sh script. Check to see the paths used
in that script is appropriate to your system.
2.8) When I try to start the postmaster, I get IpcMemoryCreate errors.
You either do not have shared memory configured properly in 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 you configure postmaster to run with. For most systems, with
default buffer sizes, you need a minimum of ~760K.
2.10) I have changed a source file, but a recompile does 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'.
_________________________________________________________________
Section 3: PostgreSQL Features
3.1) How do I specify a KEY or other constraints on a column?
Column constraints are not supported in PostgreSQL. As a consequence,
the system does not check for duplicates.
Under 6.0, create a unique index on the column. Attempts to create
duplicate of that column will report an error.
3.2) Does PostgreSQL support nested subqueries?
Subqueries are not implemented, but they can be simulated using sql
functions.
3.3) How do I define a unique indices?
PostgreSQL 6.0 supports unique indices.
3.4) I've having a lot of problems using rules.
Currently, the rule system in PostgreSQL is mostly broken. It works
enough to support the view mechanism, but that's about it. Use
PostgreSQL rules at your own peril.
3.5) I can't seem to write into the middle of large objects reliably.
The Inversion large object system in PostgreSQL is also mostly broken.
It works well enough for storing large wads of data and reading them
back out, but the implementation has some underlying problems. Use
PostgreSQL large objects at your own peril.
3.6) Does PostgreSQL have a graphical user interface? A report generator? A
embedded query language interface?
No. No. No. Not in the official distribution at least. Some users have
reported some success at using 'pgbrowse' and 'onyx' as frontends to
PostgreSQL. Several contributions are working on tk based frontend
tools. Ask on the mailing list.
3.7) How can I write client applications to PostgreSQL?
PostgreSQL supports a C-callable library interface called libpq as
well as a Tcl-based library interface called libtcl.
Others have contributed a perl interface and a WWW gateway to
PostgreSQL. See the PostgreSQL home pages for more details.
3.8) How do I prevent other hosts from accessing my PostgreSQL backend?
Use host-based authentication by modifying the file $PGDATA/pg_hba
accordingly.
3.9) How do I set up a pg_group?
Currently, there is no easy interface to set up user groups. You have
to explicitly insert/update the pg_group table. For example:
1.6) Latest release of PostgreSQL
The latest release of PostgreSQL is version 1.09. The next release will be
numbered 6.0 for historical reasons. This release is in beta and is
available at our ftp site. We expect the beta period to be complete during
the week of January 31, 1997. For information about what is new in 6.0, see
our TODO list on our WWW page.
We expect a 7.0 release in several months that will remove time-travel and
reduce by 50% the size of on-disk system columns maintained for each row in
a table. This release will also require a dump and restore.
1.7) Is there a commercial version of PostgreSQL?
Illustra Information Technology (a wholly owned subsidiary of Informix
Software, Inc.) sells an object-relational DBMS called Illustra that was
originally based on postgres. Illustra has cosmetic similarities to
PostgreSQL but has more features, is more robust, performs better, and
offers real documentation and support. On the flip side, it costs money. For
more information, contact sales@illustra.com
1.8) What documentation is available for PostgreSQL?
A user manual, manual pages, and some small test examples are included in
the distribution. The sql and built-in manual pages are particularly
important.
The www page contains pointers to an implementation guide and five papers
written about postgres design concepts and features.
1.9) What version of SQL does PostgreSQL use?
PostgreSQL supports a subset of SQL-92. It has most of the important
constructs but lacks some of the functionality. The most visible differences
are:
* no support for nested subqueries
* no HAVING clause under a GROUP BY
On the other hand, you get to create user-defined types, functions,
inheritance etc. If you're willing to help with PostgreSQL coding,
eventually we can also add the missing features listed above.
1.10) Does PostgreSQL work with databases from earlier versions of postgres?
PostgreSQL v1.09 is compatible with databases created with v1.01. Those
upgrading from 1.0 should read the directions in the MIGRATION_1.0_TO_1.02
directory.
Upgrading to 6.0 requires a dump and restore.
1.11) How many people use PostgreSQL?
Since we don't have any licensing or registration scheme, it's impossible to
tell. We do know hundreds copies of PostgreSQL v1.* have been downloaded,
and that there many hundreds of subscribers to the mailing lists.
----------------------------------------------------------------------------
Section 2: Installation Questions
2.1) initdb doesn't run
* check to see that you have the proper paths set
* check that the 'postgres' user owns all the right files
* ensure that there are files in $PGDATA/files, and that they are
non-empty. If they aren't, then "gmake install" failed for some reason
2.2) when I start up the postmaster, I get "FindBackend: could not find a
backend to execute..." "postmaster: could not find backend to execute..."
You probably do not have the right path set up. The 'postgres' executable
needs to be in your path.
2.3) The system seems to be confused about commas, decimal points, and date
formats.
Check your locale configuration. PostgreSQL uses the locale settings of the
user that ran the postmaster process. Set those accordingly for your
operating environment.
2.4) How do I install PostgreSQL somewhere other than /usr/local/pgsql?
You need to edit Makefile.global and change POSTGRESDIR accordingly, or
create a Makefile.custom and define POSTGRESDIR there.
2.5) When I run postmaster, I get a Bad System Call core dumped message.
It could be a variety of problems, but first check to see that you have
system V extensions installed on your kernel. PostgreSQL requires kernel
support for shared memory.
2.6) I get the error message "obj/fmgr.h: No such file or directory"
This indicates that you did not generate the file fmgr.h properly. Something
failed in the running of the src/backend/utils/Gen_fmgrtab.sh script. Check
to see the paths used in that script is appropriate to your system.
2.7) When I try to start the postmaster, I get IpcMemoryCreate errors.
You either do not have shared memory configured properly in 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 you configure
postmaster to run with. For most systems, with default buffer sizes, you
need a minimum of ~760K.
2.8) I have changed a source file, but a recompile does 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'.
----------------------------------------------------------------------------
Section 3: PostgreSQL Features
3.1) How do I specify a KEY or other constraints on a column?
Column constraints are not supported in PostgreSQL. As a consequence, the
system does not check for duplicates.
Under 6.0, create a unique index on the column. Attempts to create duplicate
of that column will report an error.
3.2) Does PostgreSQL support nested subqueries?
Subqueries are not implemented, but they can be simulated using sql
functions.
3.3) How do I define a unique indices?
PostgreSQL 6.0 supports unique indices.
3.4) I've having a lot of problems using rules.
Currently, the rule system in PostgreSQL is mostly broken. It works enough
to support the view mechanism, but that's about it. Use PostgreSQL rules at
your own peril.
3.5) I can't seem to write into the middle of large objects reliably.
The Inversion large object system in PostgreSQL is also mostly broken. It
works well enough for storing large wads of data and reading them back out,
but the implementation has some underlying problems. Use PostgreSQL large
objects at your own peril.
3.6) Does PostgreSQL have a graphical user interface? A report generator? A
embedded query language interface?
No. No. No. Not in the official distribution at least. Some users have
reported some success at using 'pgbrowse' and 'onyx' as frontends to
PostgreSQL. Several contributions are working on tk based frontend tools.
Ask on the mailing list.
3.7) How can I write client applications to PostgreSQL?
PostgreSQL supports a C-callable library interface called libpq as well as a
Tcl-based library interface called libtcl.
Others have contributed a perl interface and a WWW gateway to PostgreSQL.
See the PostgreSQL home pages for more details.
3.8) How do I prevent other hosts from accessing my PostgreSQL backend?
Use host-based authentication by modifying the file $PGDATA/pg_hba
accordingly.
3.9) How do I set up a pg_group?
Currently, there is no easy interface to set up user groups. You have to
explicitly insert/update the pg_group table. For example:
jolly=> insert into pg_group (groname, grosysid, grolist) jolly=> insert into pg_group (groname, grosysid, grolist)
jolly=> values ('posthackers', '1234', '{5443, 8261}'); jolly=> values ('posthackers', '1234', '{5443, 8261}');
...@@ -547,180 +425,145 @@ Section 3: PostgreSQL Features ...@@ -547,180 +425,145 @@ Section 3: PostgreSQL Features
CHANGE CHANGE
jolly=> jolly=>
The fields in pg_group are:
The fields in pg_group are: * groname: the group name. This a char16 and should be purely
* groname: the group name. This a char16 and should be purely alphanumeric. Do not include underscores or other punctuation.
alphanumeric. Do not include underscores or other punctuation. * grosysid: the group id. This is an int4. This should be unique for each
* grosysid: the group id. This is an int4. This should be unique for group.
each group. * grolist: the list of pg_user id's that belong in the group. This is an
* grolist: the list of pg_user id's that belong in the group. This int4[].
is an int4[].
3.10) What is the exact difference between binary cursors and normal
cursors?
3.10) What is the exact difference between binary cursors and normal cursors? Normal cursors return data back in ASCII format. Since data is stored
natively in binary format, the system must do a conversion to produce the
ASCII format. In addition, ASCII formats are often large in size than binary
format. Once the attributes come back in ASCII, often the client application
Normal cursors return data back in ASCII format. Since data is stored then has to convert it to a binary format to manipulate it anyway.
natively in binary format, the system must do a conversion to produce
the ASCII format. In addition, ASCII formats are often large in size Binary cursors give you back the data in the native binary representation.
than binary format. Once the attributes come back in ASCII, often the Thus, binary cursors will tend to be a little faster since there's less
client application then has to convert it to a binary format to overhead of conversion.
manipulate it anyway.
However, ASCII is architectural neutral whereas binary representation can
Binary cursors give you back the data in the native binary differ between different machine architecture. Thus, if your client machine
representation. Thus, binary cursors will tend to be a little faster uses a different representation than you server machine, getting back
since there's less overhead of conversion. attributes in binary format is probably not what you want. Also, if your
main purpose is displaying the data in ASCII, then getting it back in ASCII
However, ASCII is architectural neutral whereas binary representation will save you some effort on the client side.
can differ between different machine architecture. Thus, if your
client machine uses a different representation than you server 3.11) Why doesn't the != operator work?
machine, getting back attributes in binary format is probably not what
you want. Also, if your main purpose is displaying the data in ASCII, SQL specifies <> as the inequality operator, and that is what we have
then getting it back in ASCII will save you some effort on the client defined for the built-in types.
side.
In 6.0, != is equivalent to <>.
3.11) Why doesn't the != operator work?
3.12) What is a R-tree index and what is it used for?
An r-tree index is used for indexing spatial data. A hash index can't handle
SQL specifies <> as the inequality operator, and that is what we have range searches. A B-tree index only handles range searches in a single
defined for the built-in types. dimension. R-tree's can handle multi-dimensional data. For example, if a
R-tree index can be built on an attribute of type 'point', the system can
In 6.0, != is equivalent to <>. more efficient answer queries like select all points within a bounding
rectangle.
3.12) What is a R-tree index and what is it used for?
The canonical paper that describes the original R-Tree design is:
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-tree's can handle multi-dimensional data. For
example, if a R-tree index can be built on an attribute of type
'point', the system can more efficient answer queries like 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." Proc 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"
3.13) What is the maximum size for a tuple?
Tuples are limited to 8K bytes. Taking into account system attributes
and other overhead, one should stay well shy of 8,000 bytes to be on
the safe side. To use attributes larger than 8K, try using the large
objects interface.
Tuples do not cross 8k boundaries so a 5k tuple will require 8k of
storage.
3.14) I defined indices but my queries don't seem to make use of them. Why?
PostgreSQL does not automatically maintain statistics. One has to make
an explicit 'vacuum' call to update the statistics. After statistics
are updated, the optimizer has a better shot at using indices. Note
that the optimizer is limited and does not use indices in some
circumstances (such as OR clauses).
If the system still does not see the index, it is probably because you
have created an index on a field with the improper *_ops type. For
example, you have created a CHAR(4) field, but have specified a
char_ops index type_class.
See the create_index manual page for information on what type classes
are available. It must match the field type.
Postgres does not warn the user when the improper index is created.
Indexes not used for ORDER BY operations.
3.15) Are there ODBC drivers for PostgreSQL?
There are two ODBC drivers available, PostODBC and OpenLink ODBC.
For all people being interested in PostODBC, there are now two mailing
lists devoted to the discussion of PostODBC. The mailing lists are:
* postodbc-users@listserv.direct. net
* postodbc-developers@listse rv.direct.net
these lists are ordinary majordomo mailing lists. You can subscribe by
sending a mail to:
* majordomo@listserv.direct.net
OpenLink ODBC is currently in beta under Linux. You can get it from
http://www.openlinksw.com/postgres.html. It works with our standard
ODBC client software so you'll have Postgres ODBC available on every
client platform we support (Win, Mac, Unix, VMS).
We will probably be selling this product to people who need
commercial-quality support, but a freeware version will always be
available. Questions to postgres95@openlink.co.uk.
3.16) How do I use postgres for multi-dimensional indexing (> 2
dimensions">)?
Builtin 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 require a bit of work and we don't currently have
any documentation on how to do it.
3.17) How do I do regular expression searches? case-insensitive regexp
searching?
PostgreSQL supports the SQL LIKE syntax as well as more general
regular expression searching with the ~ operator. The !~ is the
negated regexp operator. ~* and !~* are the case-insensitive regular
expression operators.
3.18) I can't access the database as the 'root' user.
You should not create database users with user id 0(root). They will
be unable to access the database. This is a security precaution
because of the ability of any user to dynamically link object modules
into the database engine.
3.19) I experienced a server crash during a vacuum. How do I remove the lock
file?
If the server crashes during a vacuum command, chances are it will
leave a lock file hanging around. Attempts to re-run the vacuum
command result in
Guttman, A. "R-Trees: A Dynamic Index Structure for Spatial Searching." Proc
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"
3.13) What is the maximum size for a tuple?
Tuples are limited to 8K bytes. Taking into account system attributes and
other overhead, one should stay well shy of 8,000 bytes to be on the safe
side. To use attributes larger than 8K, try using the large objects
interface.
Tuples do not cross 8k boundaries so a 5k tuple will require 8k of storage.
3.14) I defined indices but my queries don't seem to make use of them. Why?
PostgreSQL does not automatically maintain statistics. One has to make an
explicit 'vacuum' call to update the statistics. After statistics are
updated, the optimizer has a better shot at using indices. Note that the
optimizer is limited and does not use indices in some circumstances (such as
OR clauses).
If the system still does not see the index, it is probably because you have
created an index on a field with the improper *_ops type. For example, you
have created a CHAR(4) field, but have specified a char_ops index
type_class.
See the create_index manual page for information on what type classes are
available. It must match the field type.
Postgres does not warn the user when the improper index is created.
Indexes not used for ORDER BY operations.
3.15) Are there ODBC drivers for PostgreSQL?
There are two ODBC drivers available, PostODBC and OpenLink ODBC.
For all people being interested in PostODBC, there are now two mailing lists
devoted to the discussion of PostODBC. The mailing lists are:
* postodbc-users@listserv.direct. net
* postodbc-developers@listse rv.direct.net
these lists are ordinary majordomo mailing lists. You can subscribe by
sending a mail to:
* majordomo@listserv.direct.net
OpenLink ODBC is currently in beta under Linux. You can get it from
http://www.openlinksw.com/postgres.html. It works with our standard ODBC
client software so you'll have Postgres ODBC available on every client
platform we support (Win, Mac, Unix, VMS).
We will probably be selling this product to people who need
commercial-quality support, but a freeware version will always be available.
Questions to postgres95@openlink.co.uk.
3.16) How do I use postgres for multi-dimensional indexing (> 2
dimensions">)?
Builtin 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 require a bit of work and we don't currently have any documentation
on how to do it.
3.17) How do I do regular expression searches? case-insensitive regexp
searching?
PostgreSQL supports the SQL LIKE syntax as well as more general regular
expression searching with the ~ operator. The !~ is the negated regexp
operator. ~* and !~* are the case-insensitive regular expression operators.
3.18) I can't access the database as the 'root' user.
You should not create database users with user id 0(root). They will be
unable to access the database. This is a security precaution because of the
ability of any user to dynamically link object modules into the database
engine.
3.19) I experienced a server crash during a vacuum. How do I remove the lock
file?
If the server crashes during a vacuum command, chances are it will leave a
lock file hanging around. Attempts to re-run the vacuum command result in
WARN:can't create lock file -- another vacuum cleaner running? WARN:can't create lock file -- another vacuum cleaner running?
If you are sure that no vacuum is actually running, you can remove the file
called "pg_vlock" in your database directory (which is $PGDATA/base/)
If you are sure that no vacuum is actually running, you can remove the
file called "pg_vlock" in your database directory (which is 3.20) What is the difference between the various character types?
$PGDATA/base/)
3.20) What is the difference between the various character types?
Type Internal Name Notes Type Internal Name Notes
-------------------------------------------------- --------------------------------------------------
...@@ -734,48 +577,35 @@ VARCHAR(#) varchar size specifies maximum length, no padding ...@@ -734,48 +577,35 @@ VARCHAR(#) varchar size specifies maximum length, no padding
TEXT text length limited only by maximum tuple length TEXT text length limited only by maximum tuple length
BYTEA bytea variable-length array of bytes BYTEA bytea variable-length array of bytes
Remember, you need to use the internal name when creating indexes on these
fields or when doing other internal operations.
Remember, you need to use the internal name when creating indexes on
these fields or when doing other internal operations.
The last four types above are "varlena" types (i.e. the first four
bytes is the length, followed by the data). CHAR(#) and VARCHAR(#)
allocate the maximum number of bytes no matter how much data is stored
in the field. TEXT and BYTEA are the only character types that have
variable length on the disk.
3.21) In a query, how do I detect if a field is NULL?
PostgreSQL has two builtin keywords, "isnull" and "notnull" (note no
spaces). Version 1.05 and later and 6.* understand IS NULL and IS NOT
NULL.
3.22) How do I see how the query optimizer is evaluating my query?
Place the word 'EXPLAIN' at the beginning of the query, for example:
The last four types above are "varlena" types (i.e. the first four bytes is
the length, followed by the data). CHAR(#) and VARCHAR(#) allocate the
maximum number of bytes no matter how much data is stored in the field. TEXT
and BYTEA are the only character types that have variable length on the
disk.
3.21) In a query, how do I detect if a field is NULL?
PostgreSQL has two builtin keywords, "isnull" and "notnull" (note no
spaces). Version 1.05 and later and 6.* understand IS NULL and IS NOT NULL.
3.22) How do I see how the query optimizer is evaluating my query?
Place the word 'EXPLAIN' at the beginning of the query, for example:
EXPLAIN SELECT * FROM table1 WHERE age = 23; EXPLAIN SELECT * FROM table1 WHERE age = 23;
3.23) How do I create a serial field?
3.23) How do I create a serial field?
Postgres does not allow the user to specifiy a user column as type
SERIAL. Instead, you can use each row's oid field as a unique value.
However, if you need to dump and reload the database, you need to be
using postgres version 1.07 or later or 6.* with pgdump's -o option or
COPY's WITH OIDS option to preserver the oids.
Another valid way of doing this is to create a function:
Postgres does not allow the user to specifiy a user column as type SERIAL.
Instead, you can use each row's oid field as a unique value. However, if you
need to dump and reload the database, you need to be using postgres version
1.07 or later or 6.* with pgdump's -o option or COPY's WITH OIDS option to
preserver the oids.
Another valid way of doing this is to create a function:
create table my_oids (f1 int4); create table my_oids (f1 int4);
insert into my_oids values (1); insert into my_oids values (1);
...@@ -783,358 +613,278 @@ BYTEA bytea variable-length array of bytes ...@@ -783,358 +613,278 @@ BYTEA bytea variable-length array of bytes
'update my_oids set f1 = f1 + 1; select f1 from my_oids; ' 'update my_oids set f1 = f1 + 1; select f1 from my_oids; '
language 'sql'; language 'sql';
then:
then:
create table my_stuff (my_key int4, value text); create table my_stuff (my_key int4, value text);
insert into my_stuff values (new_oid(), 'hello'); insert into my_stuff values (new_oid(), 'hello');
However, keep in mind there is a race condition here where one server could
do the update, then another one do an update, and they both could select the
However, keep in mind there is a race condition here where one server same new id. This statement should be performed within a transaction.
could do the update, then another one do an update, and they both
could select the same new id. This statement should be performed 3.24) How do I create a multi-column index?
within a transaction.
You can not directly create a multi-column index using create index. You
3.24) How do I create a multi-column index? need to define a function which acts on the multiple columns, then use
create index with that function.
3.25) What are the temp_XXX files in my database directory?
You can not directly create a multi-column index using create index.
You need to define a function which acts on the multiple columns, then They are temp_ files generated by the query executor. For example, if a sort
use create index with that function. needs to be done to satisfy an ORDER BY, some temp files are generated as a
result of the sort.
3.25) What are the temp_XXX files in my database directory?
If you have no transactions or sorts running at the time, it is safe to
delete the temp_ files.
They are temp_ files generated by the query executor. For example, if 3.26) Why are my table files not getting any smaller after a delete?
a sort needs to be done to satisfy an ORDER BY, some temp files are
generated as a result of the sort. If you run vacuum in pre-6.0, unused rows will be marked for reuse, but the
file blocks are not released.
If you have no transactions or sorts running at the time, it is safe
to delete the temp_ files. In 6.0, vacuum properly shrinks tables.
3.26) Why are my table files not getting any smaller after a delete?
If you run vacuum in pre-6.0, unused rows will be marked for reuse,
but the file blocks are not released.
In 6.0, vacuum properly shrinks tables.
3.27) Why can't I connect to my database from another machine?
The default configuration allows only connections from tcp/ip host
localhost. You need to add a host entry to the file pgsql/data/pg_hba.
3.28) I get the error 'default index class unsupported' when creating an
index. How do I do it?
You probably used:
3.27) Why can't I connect to my database from another machine?
The default configuration allows only connections from tcp/ip host
localhost. You need to add a host entry to the file pgsql/data/pg_hba.
3.28) I get the error 'default index class unsupported' when creating an
index. How do I do it?
You probably used:
create index idx1 on person using btree (name); create index idx1 on person using btree (name);
PostgreSQL indexes are extensible, and therefore in pre-6.0, you must
specify a class_type when creating an index. Read the manual page for create
PostgreSQL indexes are extensible, and therefore in pre-6.0, you must index (called create_index).
specify a class_type when creating an index. Read the manual page for
create index (called create_index). Version 6.0, if you do not specify a class_type, it defaults to the proper
type for the column.
Version 6.0, if you do not specify a class_type, it defaults to the
proper type for the column. 3.29) Why does creating an index crash the backend server?
3.29) Why does creating an index crash the backend server? You have probably defined an incorrect *_ops type class for the field you
are indexing.
3.30) How do I specify a decimal constant as a float8, or a string as a
You have probably defined an incorrect *_ops type class for the field text? Why am I getting poor precision?
you are indexing.
3.30) How do I specify a decimal constant as a float8, or a string as a text?
Why am I getting poor precision?
Use the :: operator. It is needed only when the default promotion
rules fail. i.e.:
Use the :: operator. It is needed only when the default promotion rules
fail. i.e.:
insert into tab1 values (4.23::float8, '2343'::text) insert into tab1 values (4.23::float8, '2343'::text)
The default floating-point constant is a float4 in releases prior to 1.05.
Later releases default to float8.
The default floating-point constant is a float4 in releases prior to
1.05. Later releases default to float8. 3.31) How do I find out what indexes or operations are defined in the
database?
3.31) How do I find out what indexes or operations are defined in the
database? Run the file pgsql/src/tutorial/syscat.source. It illustrates many of the
'select's needed to get information out of the database system tables.
3.32) My database is corrupt. I can't do anything. What should I do?
Run the file pgsql/src/tutorial/syscat.source. It illustrates many of
the 'select's needed to get information out of the database system The 1.02 release has a README file and utility that describes a possible
tables. cause of the problem and a workaround.
3.32) My database is corrupt. I can't do anything. What should I do? This bug is fixed in 1.02.1.
3.33) Createdb, destroydb, createuser,destroyuser don't run. Why?
The 1.02 release has a README file and utility that describes a
possible cause of the problem and a workaround.
This bug is fixed in 1.02.1.
3.33) Createdb, destroydb, createuser,destroyuser don't run. Why?
Release 1.02 does not have this problem.
The 1.01 release of PostgreSQL uses a variable called PAGER to filter
the output of SELECT statements. Unfortunately, this PAGER is used
even when the standard output is not a terminal.
3.34) Why does 'createuser' return 'unexpected last match in input(">)'?
You have compile postgres with flex version 2.5.3. There is bug in
this version of flex. Use flex version 2.5.2 or flex 2.5.4 instead.
There is a doc/README.flex file which will properly patch the flex
2.5.3 source code.
3.35) All my servers crash under concurrent table access. Why?
This problem can be caused by a kernel that is not configured to
support semaphores.
3.36) What tools are available for hooking postgres to Web pages?
For web integration, PHP/FI is an excellent interface. The URL for
that is http://www.vex.net/php/
PHP is great for simple stuff, but for more complex stuff, some still
use the perl interface and CGI.pm.
An example of using WWW with C to talk to Postgres is can be tried at:
* http://postgreSQL.org/~mlc
An WWW gatway based on WDB using perl can be downloaded from:
* http://www.eol.ists.ca/~dunlop/wdb -p95
3.37) What is the time-warp feature and how does it relate to vacuum?
PostgreSQL handles data changes differently than most database
systems. When a row is changed in a table, the original row is marked
with the time it was changed, and a new row is created with the
current data. By default, only current rows are used in a table. If
you specify a date/time after the table name in a FROM clause, you can
access the data that was current at that time, i.e.
Release 1.02 does not have this problem.
The 1.01 release of PostgreSQL uses a variable called PAGER to filter the
output of SELECT statements. Unfortunately, this PAGER is used even when the
standard output is not a terminal.
3.34) Why does 'createuser' return 'unexpected last match in input(">)'?
You have compile postgres with flex version 2.5.3. There is bug in this
version of flex. Use flex version 2.5.2 or flex 2.5.4 instead. There is a
doc/README.flex file which will properly patch the flex 2.5.3 source code.
3.35) All my servers crash under concurrent table access. Why?
This problem can be caused by a kernel that is not configured to support
semaphores.
3.36) What tools are available for hooking postgres to Web pages?
For web integration, PHP/FI is an excellent interface. The URL for that is
http://www.vex.net/php/
PHP is great for simple stuff, but for more complex stuff, some still use
the perl interface and CGI.pm.
An example of using WWW with C to talk to Postgres is can be tried at:
* http://postgreSQL.org/~mlc
An WWW gatway based on WDB using perl can be downloaded from:
* http://www.eol.ists.ca/~dunlop/wdb -p95
3.37) What is the time-warp feature and how does it relate to vacuum?
PostgreSQL handles data changes differently than most database systems. When
a row is changed in a table, the original row is marked with the time it was
changed, and a new row is created with the current data. By default, only
current rows are used in a table. If you specify a date/time after the table
name in a FROM clause, you can access the data that was current at that
time, i.e.
SELECT * SELECT *
FROM employees ['July 24, 1996 09:00:00'] FROM employees ['July 24, 1996 09:00:00']
displays employee rows in the table at the specified time. You can specify
intervals like [date,date], [date,], [,date], or [,]. This last option
displays employee rows in the table at the specified time. You can accesses all rows that ever existed.
specify intervals like [date,date], [date,], [,date], or [,]. This
last option accesses all rows that ever existed.
INSERTed rows get a timestamp too, so rows that were not in the table
at the desired time will not appear.
Vacuum removes rows that are no longer current. This time-warp feature
is used by the engine for rollback and crash recovery. Expiration
times can be set with purge.
In 6.0, once a table is vacuumed, the creation time of a row may be
incorrect, causing time-traval to fail.
The time-travel feature will be removed in 7.0.
3.38) How do I tune the database engine for better performance?
There are two things that can be done. You can use Openlink's option
to disable fsync() by starting the 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 shared among the backend processes. If you make
this parameter too high, the process will not start or crash
unexpectedly. Each buffer is 8K and the defualt is 64 buffers.
3.39) What debugging features are available in PostgreSQL?
PostgreSQL has several features that report status information that
can be valuable for debugging purposes.
First, by compiling with DEBUG defined, 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 the postmaster, make sure you send the
standard output and error to a log file, like:
INSERTed rows get a timestamp too, so rows that were not in the table at the
desired time will not appear.
Vacuum removes rows that are no longer current. This time-warp feature is
used by the engine for rollback and crash recovery. Expiration times can be
set with purge.
In 6.0, once a table is vacuumed, the creation time of a row may be
incorrect, causing time-traval to fail.
The time-travel feature will be removed in 7.0.
3.38) How do I tune the database engine for better performance?
There are two things that can be done. You can use Openlink's option to
disable fsync() by starting the 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 shared among the backend processes. If you make this
parameter too high, the process will not start or crash unexpectedly. Each
buffer is 8K and the defualt is 64 buffers.
3.39) What debugging features are available in PostgreSQL?
PostgreSQL has several features that report status information that can be
valuable for debugging purposes.
First, by compiling with DEBUG defined, 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 the postmaster, make sure you send the standard output
and error to a log file, like:
cd /usr/local/pgsql cd /usr/local/pgsql
./bin/postmaster >server.log 2>&1 & ./bin/postmaster >server.log 2>&1 &
This will put a server.log file in the top-level PostgreSQL directory. This
file can contain useful information about problems or errors encountered by
This will put a server.log file in the top-level PostgreSQL directory. the server. Postmaster has a -d option that allows even more detailed
This file can contain useful information about problems or errors information to be reported. The -d option takes a number 1-3 that specifies
encountered by the server. Postmaster has a -d option that allows even the debug level. The query plans in a verbose debug file can be formatted
more detailed information to be reported. The -d option takes a number using the 'indent' program. (You may need to remove the '====' lines in 1.*
1-3 that specifies the debug level. The query plans in a verbose debug releases.) Be warned that a debug level greater than one generates large log
file can be formatted using the 'indent' program. (You may need to files in 1.* releases.
remove the '====' lines in 1.* releases.) Be warned that a debug level
greater than one generates large log files in 1.* releases. You can actuall run the postgres backend from the command line, and type
your SQL statement directly. This is recommended ONLY for debugging
You can actuall run the postgres backend from the command line, and purposes. Note that a newline terminates the query, not a semicolon. If you
type your SQL statement directly. This is recommended ONLY for have compiled with debugging symbols, you can perhaps use a debugger to see
debugging purposes. Note that a newline terminates the query, not a what is happening. Because the backend was not started from the postmaster,
semicolon. If you have compiled with debugging symbols, you can it is not running in an identical environment and locking/backend
perhaps use a debugger to see what is happening. Because the backend interaction problems may not be duplicated. Some operating system can attach
was not started from the postmaster, it is not running in an identical to a running backend directly to diagnose problems.
environment and locking/backend interaction problems may not be
duplicated. Some operating system can attach to a running backend The postgres program has a -s, -A, -t options that can be very usefull for
directly to diagnose problems. debugging and performance measurements.
The postgres program has a -s, -A, -t options that can be very usefull The EXPLAIN command (see this FAQ) allows you to see how PostgreSQL is
for debugging and performance measurements. iterpreting your query.
The EXPLAIN command (see this FAQ) allows you to see how PostgreSQL is 3.40) What is an oid? What is a tid?
iterpreting your query.
Oids are Postgres's answer to unique row ids or serial columns. Every row
3.40) What is an oid? What is a tid? that is created in Postgres gets a unique oid. All oids generated by initdb
are less than 16384 (from backend/access/transam.h). All post-initdb
(user-created) oids are equal or greater that this. All these oids are
unique not only within a table, or database, but unique within the entire
Oids are Postgres's answer to unique row ids or serial columns. Every postgres installation.
row that is created in Postgres gets a unique oid. All oids generated
by initdb are less than 16384 (from backend/access/transam.h). All Postgres uses oids in its internal system tables to link rows in separate
post-initdb (user-created) oids are equal or greater that this. All tables. These oids can be used to identify specific user rows and used in
these oids are unique not only within a table, or database, but unique joins. It is recommended you use column type oid to store oid values. See
within the entire postgres installation. the sql(l) manual page to see the other internal columns.
Postgres uses oids in its internal system tables to link rows in Tids are used to indentify specific physical rows with block and offset
separate tables. These oids can be used to identify specific user rows values. Tids change after rows are modified or reloaded. They are used by
and used in joins. It is recommended you use column type oid to store index entries to point to physical rows. They can not be accessed through
oid values. See the sql(l) manual page to see the other internal sql.
columns.
3.41) What is the meaning of some of the terms used in Postgres?
Tids are used to indentify specific physical rows with block and
offset values. Tids change after rows are modified or reloaded. They Some of the source code and older documentation use terms that have more
are used by index entries to point to physical rows. They can not be common usage. Here are some:
accessed through sql.
* row, record, tuple
3.41) What is the meaning of some of the terms used in Postgres? * attribute, field, column
* table, class
* retrieve, select
* replace, update
Some of the source code and older documentation use terms that have * append, insert
more common usage. Here are some: * oid, serial value
* row, record, tuple * portal, cursor
* attribute, field, column * range variable, table name, table alias
* table, class
* retrieve, select Please let me know if you think of any more.
* replace, update
* append, insert ----------------------------------------------------------------------------
* oid, serial value
* portal, cursor Section 4: Extending PostgreSQL
* range variable, table name, table alias
4.1) I wrote a user-defined function and when I run it in psql, it dumps
core.
Please let me know if you think of any more. The problem could be a number of things. Try testing your user-defined
function in a stand alone test program first. Also, make sure you are not
sending elog NOTICES when the front-end is expecting data, such as during a
_________________________________________________________________ type_in() or type_out() functions
Section 4: Extending PostgreSQL 4.2) I get messages of the type NOTICE:PortalHeapMemoryFree: 0x402251d0 not
in alloc set!
You are pfree'ing something that was not palloc'ed. When writing
4.1) I wrote a user-defined function and when I run it in psql, it dumps user-defined functions, do not include the file "libpq-fe.h". Doing so will
core. cause your palloc to be a malloc instead of a free. Then, when the backend
pfrees the storage, you get the notice message.
4.3) I've written some nifty new types and functions for PostgreSQL.
The problem could be a number of things. Try testing your user-defined
function in a stand alone test program first. Also, make sure you are Please share them with other PostgreSQL users. Send your extensions to
not sending elog NOTICES when the front-end is expecting data, such as mailing list, and they will eventually end up in the contrib/ subdirectory.
during a type_in() or type_out() functions
4.4) How do I write a C function to return a tuple?
4.2) I get messages of the type NOTICE:PortalHeapMemoryFree: 0x402251d0 not
in alloc set! This requires extreme wizardry, so extreme that the authors have not ever
tried it, though in principle it can be done. The short answer is ... you
can't. This capability is forthcoming in the future.
You are pfree'ing something that was not palloc'ed. When writing ----------------------------------------------------------------------------
user-defined functions, do not include the file "libpq-fe.h". Doing so
will cause your palloc to be a malloc instead of a free. Then, when Section 5: Bugs
the backend pfrees the storage, you get the notice message.
5.1) How do I make a bug report?
4.3) I've written some nifty new types and functions for PostgreSQL.
Check the current FAQ at http://postgreSQL.org
Also check out our ftp site ftp://ftp.postgreSQL.org/pub to see if there is
Please share them with other PostgreSQL users. Send your extensions to a more recent PostgreSQL version.
mailing list, and they will eventually end up in the contrib/
subdirectory. You can also fill out the "bug-template" file and send it to:
4.4) How do I write a C function to return a tuple? * bugs@postgreSQL.org
This is the address of the developers mailing list.
This requires extreme wizardry, so extreme that the authors have not
ever tried it, though in principle it can be done. The short answer is
... you can't. This capability is forthcoming in the future.
_________________________________________________________________
Section 5: Bugs
5.1) How do I make a bug report?
Check the current FAQ at http://postgreSQL.org
Also check out our ftp site ftp://ftp.postgreSQL.org/pub to see if
there is a more recent PostgreSQL version.
You can also fill out the "bug-template" file and send it to:
* hackers@postgreSQL.org
This is the address of the developers mailing list.
doc/TODO
View file @ 2ffba0d4
==================================================== ====================================================
TODO list (FAQ) for PostgreSQL TODO list (FAQ) for PostgreSQL
==================================================== ====================================================
last updated: Thu Jan 2 11:19:41 EST 1997 last updated: Wed Jan 29 00:16:44 EST 1997
current maintainer: Bruce Momjian (maillist@candle.pha.pa.us) current maintainer: Bruce Momjian (maillist@candle.pha.pa.us)
...@@ -41,6 +41,9 @@ SELECT on two tables where zero or one table in WHERE and target ...@@ -41,6 +41,9 @@ SELECT on two tables where zero or one table in WHERE and target
fix system to use oid index using constant without cast to oid fix system to use oid index using constant without cast to oid
COUNT on VIEW always returns zero (maybe because there is no oid for views?) COUNT on VIEW always returns zero (maybe because there is no oid for views?)
CREATE VIEW requires super-user priviledge CREATE VIEW requires super-user priviledge
SELECT a[1] FROM test fails, it needs test.a[1]
INSERT INTO ... SELECT DISTINCT ... generates error on DISTINCT
pg_database.datdba is oid, should be int4
ENHANCEMENTS ENHANCEMENTS
------------ ------------
...@@ -48,9 +51,10 @@ Add full ANSI SQL capabilities ...@@ -48,9 +51,10 @@ Add full ANSI SQL capabilities
add subselects, possibility using temporary SQL functions add subselects, possibility using temporary SQL functions
Implement HAVING clause Implement HAVING clause
Implement EXISTS qualifier Implement EXISTS qualifier
column constraints (using rules), esp. primary keys column constraints (using rules), PRIMARY KEY during table creation
add DEFAULT, RESTRAINT, and CHECK capabilities add DEFAULT, RESTRAINT, and CHECK capabilities
report "Not implemented" if valid syntax is supplied report "Not implemented" if valid syntax is supplied
add NOT NULL to CREATE statement
add OUTER joins, left and right add OUTER joins, left and right
make VIEWs updateable where possible make VIEWs updateable where possible
add UNIONS, INTERSECTS, SUBTRACTS add UNIONS, INTERSECTS, SUBTRACTS
...@@ -117,6 +121,8 @@ Add upper/lower functions ...@@ -117,6 +121,8 @@ Add upper/lower functions
-Add table/column/function discription table indexed by oid -Add table/column/function discription table indexed by oid
-make all identifiers case-insensitive(Bruce) -make all identifiers case-insensitive(Bruce)
add pg_type attribute to identify types that need length (bpchar, varchar) add pg_type attribute to identify types that need length (bpchar, varchar)
add UNIQUE capability to non-btree indexes
improve auto-type casting
PERFORMANCE PERFORMANCE
----------- -----------
...@@ -211,6 +217,7 @@ Allow restriction on who can do backend COPY(Bryan) ...@@ -211,6 +217,7 @@ Allow restriction on who can do backend COPY(Bryan)
Can shrink tables, pg_time and pg_log(Vadim & Erich) Can shrink tables, pg_time and pg_log(Vadim & Erich)
Change debug level 2 to print queries only, changed debug heading layout(Bruce) Change debug level 2 to print queries only, changed debug heading layout(Bruce)
Change default decimal constant representation from float4 to float8(Bruce) Change default decimal constant representation from float4 to float8(Bruce)
European date format now set when postmaster is started
Execute lowercase function names if not found with exact case Execute lowercase function names if not found with exact case
Fixes for aggregate/GROUP processing, allow 'select sum(func(x),sum(x+y) from z' Fixes for aggregate/GROUP processing, allow 'select sum(func(x),sum(x+y) from z'
Gist now included in the distrubution(Marc) Gist now included in the distrubution(Marc)
...@@ -222,7 +229,7 @@ Libpq++ improvements ...@@ -222,7 +229,7 @@ Libpq++ improvements
New options to initdb(Bryan) New options to initdb(Bryan)
Pg_dump allow dump of oid's(Bruce) Pg_dump allow dump of oid's(Bruce)
Pg_dump create indexes after tables are loaded for speed(Bruce) Pg_dump create indexes after tables are loaded for speed(Bruce)
Pg_dump(Bruce) Pg_dumpall dumps all databases, and the user table
Pginterface additions for NULL values(Bruce) Pginterface additions for NULL values(Bruce)
Prevent postmaster from being run as root Prevent postmaster from being run as root
Psql \h and \? is now readable(Bruce) Psql \h and \? is now readable(Bruce)
...@@ -237,6 +244,7 @@ Remove compile-time parameters to enable binary distributions(Bryan) ...@@ -237,6 +244,7 @@ Remove compile-time parameters to enable binary distributions(Bryan)
Reverse meaning of HBA masks(Bryan) Reverse meaning of HBA masks(Bryan)
Secure Authentication of local users(Bryan) Secure Authentication of local users(Bryan)
Speed up vacuum(Vadim) Speed up vacuum(Vadim)
Vacuum now had VERBOSE option(Bruce)
Source tree changes Source tree changes
------------------- -------------------
......
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