Commit 0ad017fc authored by Tom Lane's avatar Tom Lane

Update various obsolete remarks about VACUUM.

parent ea6f2e69
<!-- $Header: /cvsroot/pgsql/doc/src/sgml/backup.sgml,v 2.18 2001/11/12 19:19:39 petere Exp $ --> <!-- $Header: /cvsroot/pgsql/doc/src/sgml/backup.sgml,v 2.19 2001/11/18 22:17:30 tgl Exp $ -->
<chapter id="backup"> <chapter id="backup">
<title>Backup and Restore</title> <title>Backup and Restore</title>
...@@ -76,7 +76,7 @@ pg_dump <replaceable class="parameter">dbname</replaceable> &gt; <replaceable cl ...@@ -76,7 +76,7 @@ pg_dump <replaceable class="parameter">dbname</replaceable> &gt; <replaceable cl
running will not be in the dump. <application>pg_dump</> does not running will not be in the dump. <application>pg_dump</> does not
block other operations on the database while it is working. block other operations on the database while it is working.
(Exceptions are those operations that need to operate with an (Exceptions are those operations that need to operate with an
exclusive lock, such as <command>VACUUM</command>.) exclusive lock, such as <command>VACUUM FULL</command>.)
</para> </para>
<important> <important>
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<!-- <!--
$Header: /cvsroot/pgsql/doc/src/sgml/maintenance.sgml,v 1.6 2001/11/12 19:19:39 petere Exp $ $Header: /cvsroot/pgsql/doc/src/sgml/maintenance.sgml,v 1.7 2001/11/18 22:17:30 tgl Exp $
--> -->
<chapter id="maintenance"> <chapter id="maintenance">
...@@ -105,8 +105,8 @@ $Header: /cvsroot/pgsql/doc/src/sgml/maintenance.sgml,v 1.6 2001/11/12 19:19:39 ...@@ -105,8 +105,8 @@ $Header: /cvsroot/pgsql/doc/src/sgml/maintenance.sgml,v 1.6 2001/11/12 19:19:39
In normal <productname>PostgreSQL</productname> operation, an UPDATE or In normal <productname>PostgreSQL</productname> operation, an UPDATE or
DELETE of a row does not immediately remove the old <firstterm>tuple</> DELETE of a row does not immediately remove the old <firstterm>tuple</>
(version of the row). This approach is necessary to gain the benefits (version of the row). This approach is necessary to gain the benefits
of multiversion concurrency control (see the User's Guide): the tuple of multiversion concurrency control (see the <citetitle>User's Guide</>):
must not be deleted while the tuple must not be deleted while
it is still potentially visible to other transactions. But eventually, it is still potentially visible to other transactions. But eventually,
an outdated or deleted tuple is no longer of interest to any transaction. an outdated or deleted tuple is no longer of interest to any transaction.
The space it occupies must be reclaimed for reuse by new tuples, to avoid The space it occupies must be reclaimed for reuse by new tuples, to avoid
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<!-- <!--
$Header: /cvsroot/pgsql/doc/src/sgml/ref/analyze.sgml,v 1.3 2001/10/16 01:13:44 tgl Exp $ $Header: /cvsroot/pgsql/doc/src/sgml/ref/analyze.sgml,v 1.4 2001/11/18 22:17:30 tgl Exp $
Postgres documentation Postgres documentation
--> -->
...@@ -125,12 +125,12 @@ ANALYZE [ VERBOSE ] [ <replaceable class="PARAMETER">table</replaceable> [ (<rep ...@@ -125,12 +125,12 @@ ANALYZE [ VERBOSE ] [ <replaceable class="PARAMETER">table</replaceable> [ (<rep
just after making major changes in the contents of a table. Accurate just after making major changes in the contents of a table. Accurate
statistics will help the planner to choose the most appropriate query statistics will help the planner to choose the most appropriate query
plan, and thereby improve the speed of query processing. A common plan, and thereby improve the speed of query processing. A common
strategy is to run <command>VACUUM</command> and <command>ANALYZE</command> strategy is to run <xref linkend="sql-vacuum" endterm="sql-vacuum-title">
once a day during a low-usage time of day. and <command>ANALYZE</command> once a day during a low-usage time of day.
</para> </para>
<para> <para>
Unlike <xref linkend="sql-vacuum" endterm="sql-vacuum-title">, Unlike <command>VACUUM FULL</command>,
<command>ANALYZE</command> requires <command>ANALYZE</command> requires
only a read lock on the target table, so it can run in parallel with only a read lock on the target table, so it can run in parallel with
other activity on the table. other activity on the table.
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<!-- <!--
$Header: /cvsroot/pgsql/doc/src/sgml/ref/vacuum.sgml,v 1.20 2001/10/12 23:34:30 momjian Exp $ $Header: /cvsroot/pgsql/doc/src/sgml/ref/vacuum.sgml,v 1.21 2001/11/18 22:17:30 tgl Exp $
Postgres documentation Postgres documentation
--> -->
...@@ -207,8 +207,7 @@ NOTICE: Index <replaceable class="PARAMETER">index</replaceable>: Pages 28; ...@@ -207,8 +207,7 @@ NOTICE: Index <replaceable class="PARAMETER">index</replaceable>: Pages 28;
intended usage is in connection with preparation of user-defined template intended usage is in connection with preparation of user-defined template
databases, or other databases that are completely read-only and will not databases, or other databases that are completely read-only and will not
receive routine maintenance <command>VACUUM</> operations. receive routine maintenance <command>VACUUM</> operations.
See <xref linkend="sql-createdatabase" endterm="sql-createdatabase-title"> See the <citetitle>Administrator's Guide</> for details.
for details.
</para> </para>
<refsect2 id="R2-SQL-VACUUM-3"> <refsect2 id="R2-SQL-VACUUM-3">
...@@ -222,8 +221,7 @@ NOTICE: Index <replaceable class="PARAMETER">index</replaceable>: Pages 28; ...@@ -222,8 +221,7 @@ NOTICE: Index <replaceable class="PARAMETER">index</replaceable>: Pages 28;
<para> <para>
We recommend that active production databases be We recommend that active production databases be
<command>VACUUM</command>-ed frequently (at least nightly), in order to <command>VACUUM</command>-ed frequently (at least nightly), in order to
remove expired rows. After copying a large table into remove expired rows. After adding or deleting a large number
<productname>Postgres</productname> or after deleting a large number
of records, it may be a good idea to issue a <command>VACUUM of records, it may be a good idea to issue a <command>VACUUM
ANALYZE</command> command for the affected table. This will update the ANALYZE</command> command for the affected table. This will update the
system catalogs with system catalogs with
...@@ -254,19 +252,19 @@ NOTICE: Index <replaceable class="PARAMETER">index</replaceable>: Pages 28; ...@@ -254,19 +252,19 @@ NOTICE: Index <replaceable class="PARAMETER">index</replaceable>: Pages 28;
<programlisting> <programlisting>
regression=> VACUUM VERBOSE ANALYZE onek; regression=> VACUUM VERBOSE ANALYZE onek;
NOTICE: --Relation onek-- NOTICE: --Relation onek--
NOTICE: Pages 98: Changed 25, Reapped 74, Empty 0, New 0; NOTICE: Index onek_unique1: Pages 14; Tuples 1000: Deleted 3000.
Tup 1000: Vac 3000, Crash 0, UnUsed 0, MinLen 188, MaxLen 188; CPU 0.00s/0.11u sec elapsed 0.12 sec.
Re-using: Free/Avail. Space 586952/586952; EndEmpty/Avail. Pages 0/74. NOTICE: Index onek_unique2: Pages 16; Tuples 1000: Deleted 3000.
Elapsed 0/0 sec. CPU 0.00s/0.10u sec elapsed 0.10 sec.
NOTICE: Index onek_stringu1: Pages 28; Tuples 1000: Deleted 3000. Elapsed 0/0 sec. NOTICE: Index onek_hundred: Pages 13; Tuples 1000: Deleted 3000.
NOTICE: Index onek_hundred: Pages 12; Tuples 1000: Deleted 3000. Elapsed 0/0 sec. CPU 0.00s/0.10u sec elapsed 0.10 sec.
NOTICE: Index onek_unique2: Pages 19; Tuples 1000: Deleted 3000. Elapsed 0/0 sec. NOTICE: Index onek_stringu1: Pages 31; Tuples 1000: Deleted 3000.
NOTICE: Index onek_unique1: Pages 17; Tuples 1000: Deleted 3000. Elapsed 0/0 sec. CPU 0.01s/0.09u sec elapsed 0.10 sec.
NOTICE: Rel onek: Pages: 98 --> 25; Tuple(s) moved: 1000. Elapsed 0/1 sec. NOTICE: Removed 3000 tuples in 70 pages.
NOTICE: Index onek_stringu1: Pages 28; Tuples 1000: Deleted 1000. Elapsed 0/0 sec. CPU 0.02s/0.04u sec elapsed 0.07 sec.
NOTICE: Index onek_hundred: Pages 12; Tuples 1000: Deleted 1000. Elapsed 0/0 sec. NOTICE: Pages 94: Changed 0, Empty 0; Tup 1000: Vac 3000, Keep 0, UnUsed 0.
NOTICE: Index onek_unique2: Pages 19; Tuples 1000: Deleted 1000. Elapsed 0/0 sec. Total CPU 0.05s/0.45u sec elapsed 0.59 sec.
NOTICE: Index onek_unique1: Pages 17; Tuples 1000: Deleted 1000. Elapsed 0/0 sec. NOTICE: Analyzing onek
VACUUM VACUUM
</programlisting> </programlisting>
</para> </para>
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