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

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.

Author: alvherre

doc/src/sgml/catalogs.sgml

@@ -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>
 

doc/src/sgml/config.sgml

@@ -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>

doc/src/sgml/maintenance.sgml

@@ -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