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Add TRUNCATE parameter to VACUUM.

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This commit adds new parameter to VACUUM command, TRUNCATE,
which specifies that VACUUM should attempt to truncate off
any empty pages at the end of the table and allow the disk space
for the truncated pages to be returned to the operating system.

This parameter, if specified, overrides the vacuum_truncate
reloption. If neither the reloption nor the VACUUM option is
used, the default is true, as before.

Author: Fujii Masao
Reviewed-by: Julien Rouhaud, Masahiko Sawada
Discussion: https://postgr.es/m/CAD21AoD+qtrSDL=GSma4Wd3kLYLeRC0hPna-YAdkDeV4z156vg@mail.gmail.com
This commit is contained in:
Fujii Masao
2019-05-08 02:10:33 +09:00
parent 98719af6c2
commit b84dbc8eb8
9 changed files with 81 additions and 10 deletions
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6
doc/src/sgml/ref/create_table.sgml
View File

@ -1418,7 +1418,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
Disabling index cleanup can speed up <command>VACUUM</command> very
significantly, but may also lead to severely bloated indexes if table
modifications are frequent. The <literal>INDEX_CLEANUP</literal>
parameter to <xref linkend="sql-vacuum"/>, if specified, overrides
parameter of <xref linkend="sql-vacuum"/>, if specified, overrides
the value of this option.
</para>
</listitem>
@ -1438,7 +1438,9 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
autovacuum do the truncation and the disk space for
the truncated pages is returned to the operating system.
Note that the truncation requires <literal>ACCESS EXCLUSIVE</literal>
lock on the table.
lock on the table. The <literal>TRUNCATE</literal> parameter
of <xref linkend="sql-vacuum"/>, if specified, overrides the value
of this option.
</para>
</listitem>
</varlistentry>

19
doc/src/sgml/ref/vacuum.sgml
View File

@ -33,6 +33,7 @@ VACUUM [ FULL ] [ FREEZE ] [ VERBOSE ] [ ANALYZE ] [ <replaceable class="paramet
DISABLE_PAGE_SKIPPING [ <replaceable class="parameter">boolean</replaceable> ]
SKIP_LOCKED [ <replaceable class="parameter">boolean</replaceable> ]
INDEX_CLEANUP [ <replaceable class="parameter">boolean</replaceable> ]
TRUNCATE [ <replaceable class="parameter">boolean</replaceable> ]
<phrase>and <replaceable class="parameter">table_and_columns</replaceable> is:</phrase>
@ -204,6 +205,24 @@ VACUUM [ FULL ] [ FREEZE ] [ VERBOSE ] [ ANALYZE ] [ <replaceable class="paramet
</listitem>
</varlistentry>
<varlistentry>
<term><literal>TRUNCATE</literal></term>
<listitem>
<para>
Specifies that <command>VACUUM</command> should attempt to
truncate off any empty pages at the end of the table and allow
the disk space for the truncated pages to be returned to
the operating system. This is normally the desired behavior
and is the default unless the <literal>vacuum_truncate</literal>
option has been set to false for the table to be vacuumed.
Setting this option to false may be useful to avoid
<literal>ACCESS EXCLUSIVE</literal> lock on the table that
the truncation requires. This option is ignored if the
<literal>FULL</literal> option is used.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">boolean</replaceable></term>
<listitem>