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Postgres FD Implementation
Commit 189c3481 authored by Bruce Momjian's avatar Bruce Momjian
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Updates from Ian Barwick.

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doc/FAQ
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Frequently Asked Questions (FAQ) for PostgreSQL Frequently Asked Questions (FAQ) for PostgreSQL
Last updated: Sat Oct 19 22:58:02 EDT 2002 Last updated: Sun Oct 20 20:47:14 EDT 2002
Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us) Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us)
...@@ -339,7 +339,7 @@ ...@@ -339,7 +339,7 @@
the Features section above. We are built for reliability and the Features section above. We are built for reliability and
features, though we continue to improve performance in every features, though we continue to improve performance in every
release. There is an interesting Web page comparing PostgreSQL release. There is an interesting Web page comparing PostgreSQL
to MySQL at http://openacs.org/why-not-mysql.html to MySQL at http://openacs.org/philosophy/why-not-mysql.html
Reliability Reliability
We realize that a DBMS must be reliable, or it is worthless. We We realize that a DBMS must be reliable, or it is worthless. We
...@@ -596,12 +596,12 @@ ...@@ -596,12 +596,12 @@
was 64, and changing it required a rebuild after altering the was 64, and changing it required a rebuild after altering the
MaxBackendId constant in include/storage/sinvaladt.h. MaxBackendId constant in include/storage/sinvaladt.h.
3.9) What are the pgsql_tmp directory? 3.9) What is in the pgsql_tmp directory?
They are temporary files generated by the query executor. For example, This directory contains temporary files generated by the query
if a sort needs to be done to satisfy an ORDER BY, and the sort executor. For example, if a sort needs to be done to satisfy an ORDER
requires more space than the backend's -S parameter allows, then BY and the sort requires more space than the backend's -S parameter
temporary files are created to hold the extra data. allows, then temporary files are created here to hold the extra data.
The temporary files are usually deleted automatically, but might The temporary files are usually deleted automatically, but might
remain if a backend crashes during a sort. A stop and restart of the remain if a backend crashes during a sort. A stop and restart of the
...@@ -758,18 +758,15 @@ ...@@ -758,18 +758,15 @@
When using wild-card operators such as LIKE or ~, indexes can only be When using wild-card operators such as LIKE or ~, indexes can only be
used in certain circumstances: used in certain circumstances:
* The beginning of the search string must be anchored to the start * The beginning of the search string must be anchored to the start
of the string, i.e.: of the string, i.e.
+ LIKE patterns must not start with %.
* LIKE patterns must not start with %. + ~ (regular expression) patterns must start with ^.
* ~ (regular expression) patterns must start with ^. * The search string can not start with a character class, e.g.
[a-e].
The search string can not start with a character class, e.g. [a-e]. * Case-insensitive searches such as ILIKE and ~* do not utilise
Case-insensitive searches such as ILIKE and ~* do not utilise
indexes. Instead, use functional indexes, which are described in indexes. Instead, use functional indexes, which are described in
section 4.12. section 4.12.
* The default C locale must be used during initdb.
The default C locale must be used during initdb.
4.9) How do I see how the query optimizer is evaluating my query? 4.9) How do I see how the query optimizer is evaluating my query?
...@@ -1057,7 +1054,7 @@ CREATE TABLE test (x int, modtime timestamp DEFAULT CURRENT_TIMESTAMP ); ...@@ -1057,7 +1054,7 @@ CREATE TABLE test (x int, modtime timestamp DEFAULT CURRENT_TIMESTAMP );
Because PostgreSQL loads database-specific system catalogs, it is Because PostgreSQL loads database-specific system catalogs, it is
uncertain how a cross-database query should even behave. uncertain how a cross-database query should even behave.
/contrib/dblink allows cross-database queries using function calls. Of contrib/dblink allows cross-database queries using function calls. Of
course, a client can make simultaneous connections to different course, a client can make simultaneous connections to different
databases and merge the results on the client side. databases and merge the results on the client side.
...@@ -1089,8 +1086,8 @@ CREATE TABLE test (x int, modtime timestamp DEFAULT CURRENT_TIMESTAMP ); ...@@ -1089,8 +1086,8 @@ CREATE TABLE test (x int, modtime timestamp DEFAULT CURRENT_TIMESTAMP );
4.28) What encryption options are available? 4.28) What encryption options are available?
* /contrib/pgcrypto contains many encryption functions for use in * contrib/pgcrypto contains many encryption functions for use in SQL
SQL queries. queries.
* The only way to encrypt transmission from the client to the server * The only way to encrypt transmission from the client to the server
is by using hostssl in pg_hba.conf. is by using hostssl in pg_hba.conf.
* Database user passwords are automatically encrypted when stored in * Database user passwords are automatically encrypted when stored in
......
doc/src/FAQ/FAQ.html
View file @ 189c3481
<!DOCTYPE html PUBLIC "-//W3C//DTD html 4.01 transitional//EN"> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<HTML> <HTML>
<!-- DOCTYPE html PUBLIC "-//W3C//DTD HTML 3.2//EN" -->
<!-- HTML -->
<HEAD> <HEAD>
<META name="generator" content="HTML Tidy, see www.w3.org"> <META name="generator" content="HTML Tidy, see www.w3.org">
<META http-equiv="Content-Type" content="text/html; charset=US-ASCII">
<TITLE>PostgreSQL FAQ</TITLE> <TITLE>PostgreSQL FAQ</TITLE>
</HEAD> </HEAD>
...@@ -14,7 +10,7 @@ ...@@ -14,7 +10,7 @@
alink="#0000ff"> alink="#0000ff">
<H1>Frequently Asked Questions (FAQ) for PostgreSQL</H1> <H1>Frequently Asked Questions (FAQ) for PostgreSQL</H1>
<P>Last updated: Sat Oct 19 22:58:02 EDT 2002</P> <P>Last updated: Sun Oct 20 20:47:14 EDT 2002</P>
<P>Current maintainer: Bruce Momjian (<A href= <P>Current maintainer: Bruce Momjian (<A href=
"mailto:pgman@candle.pha.pa.us">pgman@candle.pha.pa.us</A>)<BR> "mailto:pgman@candle.pha.pa.us">pgman@candle.pha.pa.us</A>)<BR>
...@@ -440,9 +436,8 @@ ...@@ -440,9 +436,8 @@
<I>Features</I> section above. We are built for reliability and <I>Features</I> section above. We are built for reliability and
features, though we continue to improve performance in every features, though we continue to improve performance in every
release. There is an interesting Web page comparing PostgreSQL to release. There is an interesting Web page comparing PostgreSQL to
MySQL at <A href= "http://openacs.org/why-not-mysql.html"> MySQL at <A href="http://openacs.org/philosophy/why-not-mysql.html">
http://openacs.org/philosophy/why-not-mysql.html</A><BR>
http://openacs.org/why-not-mysql.html</A><BR>
<BR> <BR>
</DD> </DD>
...@@ -653,7 +648,7 @@ ...@@ -653,7 +648,7 @@
<P>If you are doing many <SMALL>INSERTs</SMALL>, consider doing <P>If you are doing many <SMALL>INSERTs</SMALL>, consider doing
them in a large batch using the <SMALL>COPY</SMALL> command. This them in a large batch using the <SMALL>COPY</SMALL> command. This
is much faster than individual <SMALL>INSERTS.</SMALL> Second, is much faster than individual <SMALL>INSERTS</SMALL>. Second,
statements not in a <SMALL>BEGIN WORK/COMMIT</SMALL> transaction statements not in a <SMALL>BEGIN WORK/COMMIT</SMALL> transaction
block are considered to be in their own transaction. Consider block are considered to be in their own transaction. Consider
performing several statements in a single transaction block. This performing several statements in a single transaction block. This
...@@ -721,7 +716,7 @@ ...@@ -721,7 +716,7 @@
<P>If <I>postmaster</I> is running, start <I>psql</I> in one <P>If <I>postmaster</I> is running, start <I>psql</I> in one
window, then find the <SMALL>PID</SMALL> of the <I>postgres</I> window, then find the <SMALL>PID</SMALL> of the <I>postgres</I>
process used by <I>psql</I>. Use a debugger to attach to the process used by <I>psql</I>. Use a debugger to attach to the
<I>postgres</I> <SMALL>PID.</SMALL> You can set breakpoints in the <I>postgres</I> <SMALL>PID</SMALL>. You can set breakpoints in the
debugger and issue queries from <I>psql</I>. If you are debugging debugger and issue queries from <I>psql</I>. If you are debugging
<I>postgres</I> startup, you can set PGOPTIONS="-W n", then start <I>postgres</I> startup, you can set PGOPTIONS="-W n", then start
<I>psql</I>. This will cause startup to delay for <I>n</I> seconds <I>psql</I>. This will cause startup to delay for <I>n</I> seconds
...@@ -759,7 +754,7 @@ ...@@ -759,7 +754,7 @@
maximum number of processes, <SMALL>NPROC;</SMALL> the maximum maximum number of processes, <SMALL>NPROC;</SMALL> the maximum
number of processes per user, <SMALL>MAXUPRC;</SMALL> and the number of processes per user, <SMALL>MAXUPRC;</SMALL> and the
maximum number of open files, <SMALL>NFILE</SMALL> and maximum number of open files, <SMALL>NFILE</SMALL> and
<SMALL>NINODE.</SMALL> The reason that PostgreSQL has a limit on <SMALL>NINODE</SMALL>. The reason that PostgreSQL has a limit on
the number of allowed backend processes is so your system won't run the number of allowed backend processes is so your system won't run
out of resources.</P> out of resources.</P>
...@@ -768,14 +763,13 @@ ...@@ -768,14 +763,13 @@
the MaxBackendId constant in the MaxBackendId constant in
<I>include/storage/sinvaladt.h</I>.</P> <I>include/storage/sinvaladt.h</I>.</P>
<H4><A name="3.9">3.9</A>) What are the <I>pgsql_tmp</I> <H4><A name="3.9">3.9</A>) What is in the <I>pgsql_tmp</I> directory?</H4>
directory?</H4>
<P>They are temporary files generated by the query executor. For <P>This directory contains temporary files generated by the query
example, if a sort needs to be done to satisfy an <SMALL>ORDER executor. For example, if a sort needs to be done to satisfy an
BY,</SMALL> and the sort requires more space than the backend's <SMALL>ORDER BY</SMALL> and the sort requires more space than the
<I>-S</I> parameter allows, then temporary files are created to backend's <I>-S</I> parameter allows, then temporary files are created
hold the extra data.</P> here to hold the extra data.</P>
<P>The temporary files are usually deleted automatically, but might <P>The temporary files are usually deleted automatically, but might
remain if a backend crashes during a sort. A stop and restart of the remain if a backend crashes during a sort. A stop and restart of the
...@@ -815,7 +809,7 @@ ...@@ -815,7 +809,7 @@
<P>The entire query may have to be evaluated, even if you only want <P>The entire query may have to be evaluated, even if you only want
the first few rows. Consider using a query that has an <SMALL>ORDER the first few rows. Consider using a query that has an <SMALL>ORDER
BY.</SMALL> If there is an index that matches the <SMALL>ORDER BY</SMALL>. If there is an index that matches the <SMALL>ORDER
BY</SMALL>, PostgreSQL may be able to evaluate only the first few BY</SMALL>, PostgreSQL may be able to evaluate only the first few
records requested, or the entire query may have to be evaluated records requested, or the entire query may have to be evaluated
until the desired rows have been generated.</P> until the desired rows have been generated.</P>
...@@ -955,22 +949,22 @@ ...@@ -955,22 +949,22 @@
</PRE> </PRE>
<P>When using wild-card operators such as <SMALL>LIKE</SMALL> or <P>When using wild-card operators such as <SMALL>LIKE</SMALL> or
<I>~</I>, indexes can only be used in certain circumstances: <I>~</I>, indexes can only be used in certain circumstances:</P>
<UL> <UL>
<LI>The beginning of the search string must be anchored to the start <LI>The beginning of the search string must be anchored to the start
of the string, i.e.:</LI> of the string, i.e.
<UL> <UL>
<LI><SMALL>LIKE</SMALL> patterns must not start with <I>%.</I></LI> <LI><SMALL>LIKE</SMALL> patterns must not start with <I>%</I>.</LI>
<LI><I>~</I> (regular expression) patterns must start with <LI><I>~</I> (regular expression) patterns must start with
<I>^.</I></LI> <I>^</I>.</LI>
</UL> </UL></LI>
<LI>The search string can not start with a character class, <LI>The search string can not start with a character class,
e.g. [a-e].</LI> e.g. [a-e].</LI>
<LI>Case-insensitive searches such as <SMALL>ILIKE</SMALL> and <LI>Case-insensitive searches such as <SMALL>ILIKE</SMALL> and
<I>~*</I> do not utilise indexes. Instead, use functional <I>~*</I> do not utilise indexes. Instead, use functional
indexes, which are described in section <a href="#4.12">4.12</a>.</LI> indexes, which are described in section <a href="#4.12">4.12</a>.</LI>
<LI>The default <I>C</I> locale must be used during <LI>The default <I>C</I> locale must be used during
<i>initdb.</i></LI> <i>initdb</i>.</LI>
</UL> </UL>
<P> <P>
...@@ -1342,7 +1336,7 @@ BYTEA bytea variable-length byte array (null-byte safe) ...@@ -1342,7 +1336,7 @@ BYTEA bytea variable-length byte array (null-byte safe)
Because PostgreSQL loads database-specific system catalogs, it is Because PostgreSQL loads database-specific system catalogs, it is
uncertain how a cross-database query should even behave.</P> uncertain how a cross-database query should even behave.</P>
<P><I>/contrib/dblink</I> allows cross-database queries using <P><I>contrib/dblink</I> allows cross-database queries using
function calls. Of course, a client can make simultaneous function calls. Of course, a client can make simultaneous
connections to different databases and merge the results on the connections to different databases and merge the results on the
client side.</P> client side.</P>
...@@ -1379,13 +1373,13 @@ BYTEA bytea variable-length byte array (null-byte safe) ...@@ -1379,13 +1373,13 @@ BYTEA bytea variable-length byte array (null-byte safe)
<H4><A name="4.28">4.28</A>) What encryption options are available? <H4><A name="4.28">4.28</A>) What encryption options are available?
</H4> </H4>
<UL> <UL>
<LI><I>/contrib/pgcrypto</I> contains many encryption functions for <LI><I>contrib/pgcrypto</I> contains many encryption functions for
use in <SMALL>SQL</SMALL> queries.</LI> use in <SMALL>SQL</SMALL> queries.</LI>
<LI>The only way to encrypt transmission from the client to the <LI>The only way to encrypt transmission from the client to the
server is by using <I>hostssl</I> in <I>pg_hba.conf</I>.</LI> server is by using <I>hostssl</I> in <I>pg_hba.conf</I>.</LI>
<LI>Database user passwords are automatically encrypted when stored <LI>Database user passwords are automatically encrypted when stored
in version 7.3. In previous versions, you must enable the option in version 7.3. In previous versions, you must enable the option
<i>PASSWORD_ENCRYPTION</i> in <i>postgresql.conf</i>.</LI> <I>PASSWORD_ENCRYPTION</I> in <I>postgresql.conf</I>.</LI>
<LI>The server can run using an encrypted file system.</LI> <LI>The server can run using an encrypted file system.</LI>
</UL> </UL>
...@@ -1413,7 +1407,7 @@ BYTEA bytea variable-length byte array (null-byte safe) ...@@ -1413,7 +1407,7 @@ BYTEA bytea variable-length byte array (null-byte safe)
functions are fully supported in C, PL/PgSQL, and SQL. See the functions are fully supported in C, PL/PgSQL, and SQL. See the
Programmer's Guide for more information. An example of a Programmer's Guide for more information. An example of a
table-returning function defined in C can be found in table-returning function defined in C can be found in
contrib/tablefunc.</P> <I>contrib/tablefunc</I>.</P>
<H4><A name="5.4">5.4</A>) I have changed a source file. Why does <H4><A name="5.4">5.4</A>) I have changed a source file. Why does
the recompile not see the change?</H4> the recompile not see the change?</H4>
......
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