diff options
| -rw-r--r-- | doc/src/sgml/catalogs.sgml | 30 |
1 files changed, 22 insertions, 8 deletions
diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml index 29dd25f1cb4..de045d7057d 100644 --- a/doc/src/sgml/catalogs.sgml +++ b/doc/src/sgml/catalogs.sgml @@ -1,4 +1,4 @@ -<!-- $PostgreSQL: pgsql/doc/src/sgml/catalogs.sgml,v 2.160 2008/01/29 13:03:50 petere Exp $ --> +<!-- $PostgreSQL: pgsql/doc/src/sgml/catalogs.sgml,v 2.161 2008/01/31 18:40:02 tgl Exp $ --> <!-- Documentation of the system catalogs, directed toward PostgreSQL developers --> @@ -1245,6 +1245,14 @@ 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> @@ -1270,7 +1278,8 @@ <entry><structfield>enabled</structfield></entry> <entry><type>bool</type></entry> <entry></entry> - <entry>If false, this table is never autovacuumed</entry> + <entry>If false, this table will not be autovacuumed, except + to prevent transaction ID wraparound</entry> </row> <row> @@ -1352,7 +1361,9 @@ 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. The system will launch autovacuum to perform + 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. @@ -1364,12 +1375,15 @@ 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</>. + 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. + <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> |