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Update autovacuum to use reloptions instead of a system catalog, for

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per-table overrides of parameters.

This removes a whole class of problems related to misusing the catalog,
and perhaps more importantly, gives us pg_dump support for the parameters.

Based on a patch by Euler Taveira de Oliveira, heavily reworked by me.
This commit is contained in:
Alvaro Herrera
2009-02-09 20:57:59 +00:00
parent 57b10ebcd4
commit 834a6da4f7
13 changed files with 421 additions and 483 deletions
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179
doc/src/sgml/catalogs.sgml
View File

@@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/catalogs.sgml,v 2.196 2009/02/07 19:27:25 momjian Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/catalogs.sgml,v 2.197 2009/02/09 20:57:59 alvherre Exp $ -->
<!--
Documentation of the system catalogs, directed toward PostgreSQL developers
-->
@@ -88,11 +88,6 @@
<entry>authorization identifier membership relationships</entry>
</row>
<row>
<entry><link linkend="catalog-pg-autovacuum"><structname>pg_autovacuum</structname></link></entry>
<entry>per-relation autovacuum configuration parameters</entry>
</row>
<row>
<entry><link linkend="catalog-pg-cast"><structname>pg_cast</structname></link></entry>
<entry>casts (data type conversions)</entry>
@@ -1256,178 +1251,6 @@
</sect1>
<sect1 id="catalog-pg-autovacuum">
<title><structname>pg_autovacuum</structname></title>
<indexterm zone="catalog-pg-autovacuum">
<primary>pg_autovacuum</primary>
</indexterm>
<indexterm zone="catalog-pg-autovacuum">
<primary>autovacuum</primary>
<secondary>table-specific configuration</secondary>
</indexterm>
<para>
The catalog <structname>pg_autovacuum</structname> stores optional
per-relation configuration parameters for the autovacuum daemon.
If there is an entry here for a particular relation, the given
parameters will be used for autovacuuming that table. If no entry
is present, the system-wide defaults will be used. For more information
about the autovacuum daemon, see <xref linkend="autovacuum">.
</para>
<note>
<para>
It is likely that <structname>pg_autovacuum</structname> will disappear
in a future release, with the information instead being kept in
<structname>pg_class</>.<structfield>reloptions</> entries.
</para>
</note>
<table>
<title><structname>pg_autovacuum</> Columns</title>
<tgroup cols="4">
<thead>
<row>
<entry>Name</entry>
<entry>Type</entry>
<entry>References</entry>
<entry>Description</entry>
</row>
</thead>
<tbody>
<row>
<entry><structfield>vacrelid</structfield></entry>
<entry><type>oid</type></entry>
<entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.oid</literal></entry>
<entry>The table this entry is for</entry>
</row>
<row>
<entry><structfield>enabled</structfield></entry>
<entry><type>bool</type></entry>
<entry></entry>
<entry>If false, this table will not be autovacuumed, except
to prevent transaction ID wraparound</entry>
</row>
<row>
<entry><structfield>vac_base_thresh</structfield></entry>
<entry><type>integer</type></entry>
<entry></entry>
<entry>Minimum number of modified tuples before vacuum</entry>
</row>
<row>
<entry><structfield>vac_scale_factor</structfield></entry>
<entry><type>float4</type></entry>
<entry></entry>
<entry>Multiplier for <structfield>reltuples</> to add to
<structfield>vac_base_thresh</></entry>
</row>
<row>
<entry><structfield>anl_base_thresh</structfield></entry>
<entry><type>integer</type></entry>
<entry></entry>
<entry>Minimum number of modified tuples before analyze</entry>
</row>
<row>
<entry><structfield>anl_scale_factor</structfield></entry>
<entry><type>float4</type></entry>
<entry></entry>
<entry>Multiplier for <structfield>reltuples</> to add to
<structfield>anl_base_thresh</></entry>
</row>
<row>
<entry><structfield>vac_cost_delay</structfield></entry>
<entry><type>integer</type></entry>
<entry></entry>
<entry>Custom <varname>vacuum_cost_delay</> parameter</entry>
</row>
<row>
<entry><structfield>vac_cost_limit</structfield></entry>
<entry><type>integer</type></entry>
<entry></entry>
<entry>Custom <varname>vacuum_cost_limit</> parameter</entry>
</row>
<row>
<entry><structfield>freeze_min_age</structfield></entry>
<entry><type>integer</type></entry>
<entry></entry>
<entry>Custom <varname>vacuum_freeze_min_age</> parameter</entry>
</row>
<row>
<entry><structfield>freeze_max_age</structfield></entry>
<entry><type>integer</type></entry>
<entry></entry>
<entry>Custom <varname>autovacuum_freeze_max_age</> parameter</entry>
</row>
<row>
<entry><structfield>freeze_table_age</structfield></entry>
<entry><type>integer</type></entry>
<entry></entry>
<entry>Custom <varname>vacuum_freeze_table_age</> parameter</entry>
</row>
</tbody>
</tgroup>
</table>
<para>
The autovacuum daemon will initiate a <command>VACUUM</> operation
on a particular table when the number of updated or deleted tuples
exceeds <structfield>vac_base_thresh</structfield> plus
<structfield>vac_scale_factor</structfield> times the number of
live tuples currently estimated to be in the relation.
Similarly, it will initiate an <command>ANALYZE</> operation
when the number of inserted, updated or deleted tuples
exceeds <structfield>anl_base_thresh</structfield> plus
<structfield>anl_scale_factor</structfield> times the number of
live tuples currently estimated to be in the relation.
</para>
<para>
Also, the autovacuum daemon will perform a <command>VACUUM</> operation
to prevent transaction ID wraparound if the table's
<structname>pg_class</>.<structfield>relfrozenxid</> field attains an age
of more than <structfield>freeze_max_age</> transactions, whether the table
has been changed or not, even if
<structname>pg_autovacuum</>.<structfield>enabled</> is set to
<literal>false</> for it. The system will launch autovacuum to perform
such <command>VACUUM</>s even if autovacuum is otherwise disabled.
See <xref linkend="vacuum-for-wraparound"> for more about wraparound
prevention.
</para>
<para>
Any of the numerical fields can contain <literal>-1</> (or indeed
any negative value) to indicate that the system-wide default should
be used for this particular value. Observe that the
<structfield>vac_cost_delay</> variable inherits its default value from the
<xref linkend="guc-autovacuum-vacuum-cost-delay"> configuration parameter,
or from <xref linkend="guc-vacuum-cost-delay"> if the former is set to a
negative value. The same applies to <structfield>vac_cost_limit</>.
Also, autovacuum will ignore attempts to set a per-table
<structfield>freeze_max_age</> larger than the system-wide setting (it can
only be set smaller), and the <structfield>freeze_min_age</> value will be
limited to half the system-wide <xref
linkend="guc-autovacuum-freeze-max-age"> setting. Note that while you
can set <structfield>freeze_max_age</> very small, or even zero, this
is usually unwise since it will force frequent vacuuming.
</para>
</sect1>
<sect1 id="catalog-pg-cast">
<title><structname>pg_cast</structname></title>

30
doc/src/sgml/config.sgml
View File

@@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.206 2009/01/16 13:27:23 heikki Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.207 2009/02/09 20:57:59 alvherre Exp $ -->
<chapter Id="runtime-config">
<title>Server Configuration</title>
@@ -3547,8 +3547,8 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
The default is 50 tuples.
This parameter can only be set in the <filename>postgresql.conf</>
file or on the server command line.
This setting can be overridden for individual tables by entries in
<structname>pg_autovacuum</>.
This setting can be overridden for individual tables by
changing storage parameters.
</para>
</listitem>
</varlistentry>
@@ -3565,8 +3565,8 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
The default is 50 tuples.
This parameter can only be set in the <filename>postgresql.conf</>
file or on the server command line.
This setting can be overridden for individual tables by entries in
<structname>pg_autovacuum</>.
This setting can be overridden for individual tables by
changing storage parameters.
</para>
</listitem>
</varlistentry>
@@ -3584,8 +3584,8 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
The default is 0.2 (20% of table size).
This parameter can only be set in the <filename>postgresql.conf</>
file or on the server command line.
This setting can be overridden for individual tables by entries in
<structname>pg_autovacuum</>.
This setting can be overridden for individual tables by
changing storage parameters.
</para>
</listitem>
</varlistentry>
@@ -3603,8 +3603,8 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
The default is 0.1 (10% of table size).
This parameter can only be set in the <filename>postgresql.conf</>
file or on the server command line.
This setting can be overridden for individual tables by entries in
<structname>pg_autovacuum</>.
This setting can be overridden for individual tables by
changing storage parameters.
</para>
</listitem>
</varlistentry>
@@ -3624,8 +3624,8 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
autovacuum is otherwise disabled.
The default is 200 million transactions.
This parameter can only be set at server start, but the setting
can be reduced for individual tables by entries in
<structname>pg_autovacuum</>.
can be reduced for individual tables by
changing storage parameters.
For more information see <xref linkend="vacuum-for-wraparound">.
</para>
</listitem>
@@ -3645,8 +3645,8 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
The default value is 20 milliseconds.
This parameter can only be set in the <filename>postgresql.conf</>
file or on the server command line.
This setting can be overridden for individual tables by entries in
<structname>pg_autovacuum</>.
This setting can be overridden for individual tables by
changing storage parameters.
</para>
</listitem>
</varlistentry>
@@ -3667,8 +3667,8 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
each worker never exceeds the limit on this variable.
This parameter can only be set in the <filename>postgresql.conf</>
file or on the server command line.
This setting can be overridden for individual tables by entries in
<structname>pg_autovacuum</>.
This setting can be overridden for individual tables by
changing storage parameters.
</para>
</listitem>
</varlistentry>

76
doc/src/sgml/maintenance.sgml
View File

@@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/maintenance.sgml,v 1.89 2009/01/16 13:27:23 heikki Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/maintenance.sgml,v 1.90 2009/02/09 20:57:59 alvherre Exp $ -->
<chapter id="maintenance">
<title>Routine Database Maintenance Tasks</title>
@@ -573,7 +573,9 @@ HINT: Stop the postmaster and use a standalone backend to VACUUM in "mydb".
<para>
Tables whose <structfield>relfrozenxid</> value is more than
<varname>autovacuum_freeze_max_age</> transactions old are always
vacuumed. Otherwise, if the number of tuples obsoleted since the last
vacuumed (this also applies to those tables whose freeze max age has
been modified via storage parameters; see below). Otherwise, if the
number of tuples obsoleted since the last
<command>VACUUM</command> exceeds the <quote>vacuum threshold</quote>, the
table is vacuumed. The vacuum threshold is defined as:
<programlisting>
@@ -604,65 +606,39 @@ analyze threshold = analyze base threshold + analyze scale factor * number of tu
<para>
The default thresholds and scale factors are taken from
<filename>postgresql.conf</filename>, but it is possible to override them
on a table-by-table basis by making entries in the system catalog
<link
linkend="catalog-pg-autovacuum"><structname>pg_autovacuum</></link>.
If a <structname>pg_autovacuum</structname> row exists for a particular
table, the settings it specifies are applied; otherwise the global
settings are used. See <xref linkend="runtime-config-autovacuum"> for
on a table-by-table basis; see
<xref linkend="sql-createtable-storage-parameters"
endterm="sql-createtable-storage-parameters-title"> for more information.
If a setting
has been changed via storage parameters, that value is used; otherwise the
global settings are used. See <xref linkend="runtime-config-autovacuum"> for
more details on the global settings.
</para>
<para>
Besides the base threshold values and scale factors, there are five
more parameters that can be set for each table in
<structname>pg_autovacuum</structname>.
The first, <structname>pg_autovacuum</>.<structfield>enabled</>,
Besides the base threshold values and scale factors, there are six
more autovacuum parameters that can be set for each table via
storage parameters.
The first parameter, <literal>autovacuum_enabled</>,
can be set to <literal>false</literal> to instruct the autovacuum daemon
to skip that particular table entirely. In this case
autovacuum will only touch the table if it must do so
to prevent transaction ID wraparound.
The next two parameters, the vacuum cost delay
(<structname>pg_autovacuum</structname>.<structfield>vac_cost_delay</structfield>)
and the vacuum cost limit
(<structname>pg_autovacuum</structname>.<structfield>vac_cost_limit</structfield>),
are used to set table-specific values for the
<xref linkend="runtime-config-resource-vacuum-cost" endterm="runtime-config-resource-vacuum-cost-title">
Another two parameters,
<literal>autovacuum_vacuum_cost_delay</literal> and
<literal>autovacuum_vacuum_cost_limit</literal>, are used to set
table-specific values for the
<xref linkend="runtime-config-resource-vacuum-cost"
endterm="runtime-config-resource-vacuum-cost-title">
feature.
The last two parameters,
(<structname>pg_autovacuum</structname>.<structfield>freeze_min_age</structfield>)
and
(<structname>pg_autovacuum</structname>.<structfield>freeze_max_age</structfield>),
are used to set table-specific values for
<xref linkend="guc-vacuum-freeze-min-age"> and
<xref linkend="guc-autovacuum-freeze-max-age"> respectively.
<literal>autovacuum_freeze_min_age</literal>,
<literal>autovacuum_freeze_max_age</literal> and
<literal>autovacuum_freeze_table_age</literal> are used to set
values for <xref linkend="guc-vacuum-freeze-min-age">,
<xref linkend="guc-autovacuum-freeze-max-age"> and
<xref linkend="guc-vacuum-freeze-table-age"> respectively.
</para>
<para>
If any of the values in <structname>pg_autovacuum</structname>
are set to a negative number, or if a row is not present at all in
<structname>pg_autovacuum</structname> for any particular table, the
corresponding values from <filename>postgresql.conf</filename> are used.
</para>
<para>
There is not currently any support for making
<structname>pg_autovacuum</structname> entries, except by doing
manual <command>INSERT</>s into the catalog. This feature will be
improved in future releases, and it is likely that the catalog
definition will change.
</para>
<caution>
<para>
The contents of the <structname>pg_autovacuum</structname> system
catalog are currently not saved in database dumps created by the
tools <application>pg_dump</> and <application>pg_dumpall</>. If
you want to preserve them across a dump/reload cycle, make sure
you dump the catalog manually.
</para>
</caution>
<para>
When multiple workers are running, the cost limit is
<quote>balanced</quote> among all the running workers, so that the

5
doc/src/sgml/ref/alter_table.sgml
View File

@@ -1,5 +1,5 @@
<!--
$PostgreSQL: pgsql/doc/src/sgml/ref/alter_table.sgml,v 1.102 2008/12/13 19:13:44 tgl Exp $
$PostgreSQL: pgsql/doc/src/sgml/ref/alter_table.sgml,v 1.103 2009/02/09 20:57:59 alvherre Exp $
PostgreSQL documentation
-->
@@ -286,7 +286,8 @@ where <replaceable class="PARAMETER">action</replaceable> is one of:
<listitem>
<para>
This form changes one or more storage parameters for the table. See
<xref linkend="SQL-CREATETABLE" endterm="sql-createtable-title">
<xref linkend="SQL-CREATETABLE-storage-parameters"
endterm="sql-createtable-storage-parameters-title">
for details on the available parameters. Note that the table contents
will not be modified immediately by this command; depending on the
parameter you might need to rewrite the table to get the desired effects.

129
doc/src/sgml/ref/create_table.sgml
View File

@@ -1,5 +1,5 @@
<!--
$PostgreSQL: pgsql/doc/src/sgml/ref/create_table.sgml,v 1.112 2009/02/02 19:31:38 alvherre Exp $
$PostgreSQL: pgsql/doc/src/sgml/ref/create_table.sgml,v 1.113 2009/02/09 20:57:59 alvherre Exp $
PostgreSQL documentation
-->
@@ -685,19 +685,29 @@ and <replaceable class="PARAMETER">table_constraint</replaceable> is:
<refsect2 id="SQL-CREATETABLE-storage-parameters">
<title id="SQL-CREATETABLE-storage-parameters-title">Storage Parameters</title>
<indexterm zone="sql-createtable-storage-parameters">
<primary>storage parameters</primary>
</indexterm>
<para>
The <literal>WITH</> clause can specify <firstterm>storage parameters</>
for tables, and for indexes associated with a <literal>UNIQUE</literal> or
<literal>PRIMARY KEY</literal> constraint. Storage parameters for
indexes are documented in <xref linkend="SQL-CREATEINDEX"
endterm="sql-createindex-title">. The storage parameters currently
available for tables are:
available for tables are listed below. For each parameter, there is an
additional, identically named parameter, prefixed with
<literal>toast.</literal> which can be used to control the behavior of the
supplementary storage table, if any; see <xref linkend="storage-toast">.
Note that the supplementary storage table inherits the
<literal>autovacuum</literal> values from its parent table, if there are
no <literal>toast.autovacuum_*</literal> settings set.
</para>
<variablelist>
<varlistentry>
<term><literal>FILLFACTOR</></term>
<term><literal>fillfactor</>, <literal>toast.fillfactor</literal> (<type>integer</>)</term>
<listitem>
<para>
The fillfactor for a table is a percentage between 10 and 100.
@@ -715,11 +725,118 @@ and <replaceable class="PARAMETER">table_constraint</replaceable> is:
</varlistentry>
<varlistentry>
<term><literal>TOAST.FILLFACTOR</literal></term>
<term><literal>autovacuum_enabled</>, <literal>toast.autovacuum_enabled</literal> (<type>boolean</>)</term>
<listitem>
<para>
Same as above, for the supplementary storage table, if any; see
<xref linkend="storage-toast">.
Enables or disables the autovacuum daemon on a particular table.
If true, the autovacuum daemon will initiate a <command>VACUUM</> operation
on a particular table when the number of updated or deleted tuples exceeds
<literal>autovacuum_vacuum_threshold</> plus
<literal>autovacuum_vacuum_scale_factor</> times the number of live tuples
currently estimated to be in the relation.
Similarly, it will initiate an <command>ANALYZE</> operation when the
number of inserted, updated or deleted tuples exceeds
<literal>autovacuum_analyze_threshold</> plus
<literal>autovacuum_analyze_scale_factor</> times the number of live tuples
currently estimated to be in the relation.
If false, this table will not be autovacuumed, except to prevent
transaction Id wraparound. See <xref linkend="vacuum-for-wraparound"> for
more about wraparound prevention.
Observe that this variable inherits its value from the <xref
linkend="guc-autovacuum"> setting.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>autovacuum_vacuum_threshold</>, <literal>toast.autovacuum_vacuum_threshold</literal> (<type>integer</>)</term>
<listitem>
<para>
Minimum number of updated or deleted tuples before initiate a
<command>VACUUM</> operation on a particular table.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>autovacuum_vacuum_scale_factor</>, <literal>toast.autovacuum_vacuum_scale_factor</literal> (<type>float4</>)</term>
<listitem>
<para>
Multiplier for <structfield>reltuples</> to add to
<literal>autovacuum_vacuum_threshold</>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>autovacuum_analyze_threshold</>, <literal>toast.autovacuum_analyze_threshold</literal> (<type>integer</>)</term>
<listitem>
<para>
Minimum number of inserted, updated, or deleted tuples before initiate an
<command>ANALYZE</> operation on a particular table.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>autovacuum_analyze_scale_factor</>, <literal>toast.autovacuum_analyze_scale_factor</literal> (<type>float4</>)</term>
<listitem>
<para>
Multiplier for <structfield>reltuples</> to add to
<literal>autovacuum_analyze_threshold</>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>autovacuum_vacuum_cost_delay</>, <literal>toast.autovacuum_vacuum_cost_delay</literal> (<type>integer</>)</term>
<listitem>
<para>
Custom <xref linkend="guc-autovacuum-vacuum-cost-delay"> parameter.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>autovacuum_vacuum_cost_limit</>, <literal>toast.autovacuum_vacuum_cost_limit</literal> (<type>integer</>)</term>
<listitem>
<para>
Custom <xref linkend="guc-autovacuum-vacuum-cost-limit"> parameter.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>autovacuum_freeze_min_age</>, <literal>toast.autovacuum_freeze_min_age</literal> (<type>integer</>)</term>
<listitem>
<para>
Custom <xref linkend="guc-vacuum-freeze-min-age"> parameter. Note that
autovacuum will ignore attempts to set a per-table
<literal>autovacuum_freeze_min_age</> larger than the half system-wide
<xref linkend="guc-autovacuum-freeze-max-age"> setting.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>autovacuum_freeze_max_age</>, <literal>toast.autovacuum_freeze_max_age</literal> (<type>integer</>)</term>
<listitem>
<para>
Custom <xref linkend="guc-autovacuum-freeze-max-age"> parameter. Note that
autovacuum will ignore attempts to set a per-table
<literal>autovacuum_freeze_max_age</> larger than the system-wide setting
(it can only be set smaller). Note that while you can set
<literal>autovacuum_freeze_max_age</> very small, or even zero, this is
usually unwise since it will force frequent vacuuming.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>autovacuum_freeze_table_age</literal> (<type>integer</type>)</term>
<listitem>
<para>
Custom <xref linkend="guc-vacuum-freeze-table-age"> parameter.
</para>
</listitem>
</varlistentry>