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Improve documentation around autovacuum-related storage parameters.

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These were discussed in three different sections of the manual, which
unsurprisingly had diverged over time; and the descriptions of individual
variables lacked stylistic consistency even within each section (and
frequently weren't in very good English anyway).  Clean up the mess, and
remove some of the redundant information in hopes that future additions
will be less likely to re-introduce inconsistency.  For instance I see
no need for maintenance.sgml to include its very own list of all the
autovacuum storage parameters, especially since that list was already
incomplete.
This commit is contained in:
Tom Lane
2015-11-11 17:13:38 -05:00
parent da3751c8ea
commit 6404751ce9
3 changed files with 103 additions and 113 deletions
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104
doc/src/sgml/ref/create_table.sgml
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@@ -878,14 +878,14 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
Storage parameters for
indexes are documented in <xref linkend="SQL-CREATEINDEX">.
The storage parameters currently
available for tables are listed below. For each parameter, unless noted,
there is an additional parameter with the same name prefixed with
<literal>toast.</literal>, which can be used to control the behavior of the
available for tables are listed below. For many of these parameters, as
shown, there is an additional parameter with the same name prefixed with
<literal>toast.</literal>, which controls the behavior of the
table's secondary <acronym>TOAST</> table, if any
(see <xref linkend="storage-toast"> for more information about TOAST).
Note that the TOAST table uses the parameter values defined for
the main table, for each parameter applicable to TOAST tables and
for which no value is set in the TOAST table itself.
If a table parameter value is set and the
equivalent <literal>toast.</literal> parameter is not, the TOAST table
will use the table's parameter value.
</para>
<variablelist>
@@ -912,22 +912,19 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
<term><literal>autovacuum_enabled</>, <literal>toast.autovacuum_enabled</literal> (<type>boolean</>)</term>
<listitem>
<para>
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.
Enables or disables the autovacuum daemon for a particular table.
If true, the autovacuum daemon will perform automatic <command>VACUUM</>
and/or <command>ANALYZE</> operations on this table following the rules
discussed in <xref linkend="autovacuum">.
If false, this table will not be autovacuumed, except to prevent
transaction Id wraparound. See <xref linkend="vacuum-for-wraparound"> for
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.
Note that the autovacuum daemon does not run at all (except to prevent
transaction ID wraparound) if the <xref linkend="guc-autovacuum">
parameter is false; setting individual tables' storage parameters does
not override that. Therefore there is seldom much point in explicitly
setting this storage parameter to <literal>true</>, only
to <literal>false</>.
</para>
</listitem>
</varlistentry>
@@ -936,8 +933,8 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
<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.
Per-table value for <xref linkend="guc-autovacuum-vacuum-threshold">
parameter.
</para>
</listitem>
</varlistentry>
@@ -946,8 +943,8 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
<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</>.
Per-table value for <xref linkend="guc-autovacuum-vacuum-scale-factor">
parameter.
</para>
</listitem>
</varlistentry>
@@ -956,8 +953,8 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
<term><literal>autovacuum_analyze_threshold</> (<type>integer</>)</term>
<listitem>
<para>
Minimum number of inserted, updated, or deleted tuples before initiate an
<command>ANALYZE</> operation on a particular table.
Per-table value for <xref linkend="guc-autovacuum-analyze-threshold">
parameter.
</para>
</listitem>
</varlistentry>
@@ -966,8 +963,8 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
<term><literal>autovacuum_analyze_scale_factor</> (<type>float4</>)</term>
<listitem>
<para>
Multiplier for <structfield>reltuples</> to add to
<literal>autovacuum_analyze_threshold</>.
Per-table value for <xref linkend="guc-autovacuum-analyze-scale-factor">
parameter.
</para>
</listitem>
</varlistentry>
@@ -976,7 +973,8 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
<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.
Per-table value for <xref linkend="guc-autovacuum-vacuum-cost-delay">
parameter.
</para>
</listitem>
</varlistentry>
@@ -985,7 +983,8 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
<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.
Per-table value for <xref linkend="guc-autovacuum-vacuum-cost-limit">
parameter.
</para>
</listitem>
</varlistentry>
@@ -994,10 +993,11 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
<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 half the system-wide
<xref linkend="guc-autovacuum-freeze-max-age"> setting.
Per-table value for <xref linkend="guc-vacuum-freeze-min-age">
parameter. Note that autovacuum will ignore
per-table <literal>autovacuum_freeze_min_age</> parameters that are
larger than half the
system-wide <xref linkend="guc-autovacuum-freeze-max-age"> setting.
</para>
</listitem>
</varlistentry>
@@ -1006,10 +1006,10 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
<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).
Per-table value for <xref linkend="guc-autovacuum-freeze-max-age">
parameter. Note that autovacuum will ignore
per-table <literal>autovacuum_freeze_max_age</> parameters that are
larger than the system-wide setting (it can only be set smaller).
</para>
</listitem>
</varlistentry>
@@ -1018,7 +1018,8 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
<term><literal>autovacuum_freeze_table_age</literal>, <literal>toast.autovacuum_freeze_table_age</literal> (<type>integer</type>)</term>
<listitem>
<para>
Custom <xref linkend="guc-vacuum-freeze-table-age"> parameter.
Per-table value for <xref linkend="guc-vacuum-freeze-table-age">
parameter.
</para>
</listitem>
</varlistentry>
@@ -1027,9 +1028,10 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
<term><literal>autovacuum_multixact_freeze_min_age</literal>, <literal>toast.autovacuum_multixact_freeze_min_age</literal> (<type>integer</type>)</term>
<listitem>
<para>
Custom <xref linkend="guc-vacuum-multixact-freeze-min-age"> parameter.
Note that autovacuum will ignore attempts to set a per-table
<literal>autovacuum_multixact_freeze_min_age</> larger than half the
Per-table value for <xref linkend="guc-vacuum-multixact-freeze-min-age">
parameter. Note that autovacuum will ignore
per-table <literal>autovacuum_multixact_freeze_min_age</> parameters
that are larger than half the
system-wide <xref linkend="guc-autovacuum-multixact-freeze-max-age">
setting.
</para>
@@ -1040,10 +1042,12 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
<term><literal>autovacuum_multixact_freeze_max_age</literal>, <literal>toast.autovacuum_multixact_freeze_max_age</literal> (<type>integer</type>)</term>
<listitem>
<para>
Custom <xref linkend="guc-autovacuum-multixact-freeze-max-age"> parameter. Note
that autovacuum will ignore attempts to set a per-table
<literal>autovacuum_multixact_freeze_max_age</> larger than the
system-wide setting (it can only be set smaller).
Per-table value
for <xref linkend="guc-autovacuum-multixact-freeze-max-age"> parameter.
Note that autovacuum will ignore
per-table <literal>autovacuum_multixact_freeze_max_age</> parameters
that are larger than the system-wide setting (it can only be set
smaller).
</para>
</listitem>
</varlistentry>
@@ -1052,7 +1056,8 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
<term><literal>autovacuum_multixact_freeze_table_age</literal>, <literal>toast.autovacuum_multixact_freeze_table_age</literal> (<type>integer</type>)</term>
<listitem>
<para>
Custom <xref linkend="guc-vacuum-multixact-freeze-table-age"> parameter.
Per-table value
for <xref linkend="guc-vacuum-multixact-freeze-table-age"> parameter.
</para>
</listitem>
</varlistentry>
@@ -1061,7 +1066,8 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
<term><literal>log_autovacuum_min_duration</literal>, <literal>toast.log_autovacuum_min_duration</literal> (<type>integer</type>)</term>
<listitem>
<para>
Custom <xref linkend="guc-log-autovacuum-min-duration"> parameter.
Per-table value for <xref linkend="guc-log-autovacuum-min-duration">
parameter.
</para>
</listitem>
</varlistentry>
@@ -1070,7 +1076,7 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
<term><literal>user_catalog_table</literal> (<type>boolean</type>)</term>
<listitem>
<para>
Declare a table as an additional catalog table, e.g. for the purpose of
Declare the table as an additional catalog table for purposes of
logical replication. See
<xref linkend="logicaldecoding-capabilities"> for details.
This parameter cannot be set for TOAST tables.