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Fix recently-understood problems with handling of XID freezing, particularly

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in PITR scenarios.  We now WAL-log the replacement of old XIDs with
FrozenTransactionId, so that such replacement is guaranteed to propagate to
PITR slave databases.  Also, rather than relying on hint-bit updates to be
preserved, pg_clog is not truncated until all instances of an XID are known to
have been replaced by FrozenTransactionId.  Add new GUC variables and
pg_autovacuum columns to allow management of the freezing policy, so that
users can trade off the size of pg_clog against the amount of freezing work
done.  Revise the already-existing code that forces autovacuum of tables
approaching the wraparound point to make it more bulletproof; also, revise the
autovacuum logic so that anti-wraparound vacuuming is done per-table rather
than per-database.  initdb forced because of changes in pg_class, pg_database,
and pg_autovacuum catalogs.  Heikki Linnakangas, Simon Riggs, and Tom Lane.
This commit is contained in:
Tom Lane
2006-11-05 22:42:10 +00:00
parent 10c70b8602
commit 48188e1621
43 changed files with 1284 additions and 1062 deletions
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33
doc/src/sgml/ref/vacuum.sgml
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@@ -1,5 +1,5 @@
<!--
$PostgreSQL: pgsql/doc/src/sgml/ref/vacuum.sgml,v 1.42 2006/10/31 01:52:31 neilc Exp $
$PostgreSQL: pgsql/doc/src/sgml/ref/vacuum.sgml,v 1.43 2006/11/05 22:42:07 tgl Exp $
PostgreSQL documentation
-->
@@ -20,8 +20,8 @@ PostgreSQL documentation
<refsynopsisdiv>
<synopsis>
VACUUM [ FULL | FREEZE ] [ VERBOSE ] [ <replaceable class="PARAMETER">table</replaceable> ]
VACUUM [ FULL | FREEZE ] [ VERBOSE ] ANALYZE [ <replaceable class="PARAMETER">table</replaceable> [ (<replaceable class="PARAMETER">column</replaceable> [, ...] ) ] ]
VACUUM [ FULL ] [ FREEZE ] [ VERBOSE ] [ <replaceable class="PARAMETER">table</replaceable> ]
VACUUM [ FULL ] [ FREEZE ] [ VERBOSE ] ANALYZE [ <replaceable class="PARAMETER">table</replaceable> [ (<replaceable class="PARAMETER">column</replaceable> [, ...] ) ] ]
</synopsis>
</refsynopsisdiv>
@@ -62,21 +62,6 @@ VACUUM [ FULL | FREEZE ] [ VERBOSE ] ANALYZE [ <replaceable class="PARAMETER">ta
blocks. This form is much slower and requires an exclusive lock on each
table while it is being processed.
</para>
<para>
<literal>FREEZE</literal> is a special-purpose option that
causes tuples to be marked <quote>frozen</quote> as soon as possible,
rather than waiting until they are quite old. If this is done when there
are no other open transactions in the same database, then it is guaranteed
that all tuples in the database are <quote>frozen</> and will not be
subject to transaction ID wraparound problems, no matter how long the
database is left unvacuumed.
<literal>FREEZE</literal> is not recommended for routine use. Its only
intended usage is in connection with preparation of user-defined template
databases, or other databases that are completely read-only and will not
receive routine maintenance <command>VACUUM</> operations.
See <xref linkend="maintenance"> for details.
</para>
</refsect1>
<refsect1>
@@ -98,6 +83,11 @@ VACUUM [ FULL | FREEZE ] [ VERBOSE ] ANALYZE [ <replaceable class="PARAMETER">ta
<listitem>
<para>
Selects aggressive <quote>freezing</quote> of tuples.
Specifying <literal>FREEZE</literal> is equivalent to performing
<command>VACUUM</command> with the
<xref linkend="guc-vacuum-freeze-min-age"> parameter
set to zero. The <literal>FREEZE</literal> option is deprecated and
will be removed in a future release; set the parameter instead.
</para>
</listitem>
</varlistentry>
@@ -185,6 +175,13 @@ VACUUM [ FULL | FREEZE ] [ VERBOSE ] ANALYZE [ <replaceable class="PARAMETER">ta
it is sometimes advisable to use the cost-based vacuum delay feature.
See <xref linkend="runtime-config-resource-vacuum-cost"> for details.
</para>
<para>
<productname>PostgreSQL</productname> includes an <quote>autovacuum</>
facility which can automate routine vacuum maintenance. For more
information about automatic and manual vacuuming, see
<xref linkend="routine-vacuuming">.
</para>
</refsect1>
<refsect1>