diff options
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/catalogs.sgml | 7 | ||||
| -rw-r--r-- | doc/src/sgml/ref/create_aggregate.sgml | 18 |
2 files changed, 25 insertions, 0 deletions
diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml index 9388df5ac27..acc261ca516 100644 --- a/doc/src/sgml/catalogs.sgml +++ b/doc/src/sgml/catalogs.sgml @@ -373,6 +373,13 @@ <entry>Data type of the aggregate function's internal transition (state) data</entry> </row> <row> + <entry><structfield>aggtransspace</structfield></entry> + <entry><type>int4</type></entry> + <entry></entry> + <entry>Approximate average size (in bytes) of the transition state + data, or zero to use a default estimate</entry> + </row> + <row> <entry><structfield>agginitval</structfield></entry> <entry><type>text</type></entry> <entry></entry> diff --git a/doc/src/sgml/ref/create_aggregate.sgml b/doc/src/sgml/ref/create_aggregate.sgml index 2b35fa4d522..17819dd1a8e 100644 --- a/doc/src/sgml/ref/create_aggregate.sgml +++ b/doc/src/sgml/ref/create_aggregate.sgml @@ -24,6 +24,7 @@ PostgreSQL documentation CREATE AGGREGATE <replaceable class="parameter">name</replaceable> ( [ <replaceable class="parameter">argmode</replaceable> ] [ <replaceable class="parameter">arg_name</replaceable> ] <replaceable class="parameter">arg_data_type</replaceable> [ , ... ] ) ( SFUNC = <replaceable class="PARAMETER">sfunc</replaceable>, STYPE = <replaceable class="PARAMETER">state_data_type</replaceable> + [ , SSPACE = <replaceable class="PARAMETER">state_data_size</replaceable> ] [ , FINALFUNC = <replaceable class="PARAMETER">ffunc</replaceable> ] [ , INITCOND = <replaceable class="PARAMETER">initial_condition</replaceable> ] [ , SORTOP = <replaceable class="PARAMETER">sort_operator</replaceable> ] @@ -35,6 +36,7 @@ CREATE AGGREGATE <replaceable class="PARAMETER">name</replaceable> ( BASETYPE = <replaceable class="PARAMETER">base_type</replaceable>, SFUNC = <replaceable class="PARAMETER">sfunc</replaceable>, STYPE = <replaceable class="PARAMETER">state_data_type</replaceable> + [ , SSPACE = <replaceable class="PARAMETER">state_data_size</replaceable> ] [ , FINALFUNC = <replaceable class="PARAMETER">ffunc</replaceable> ] [ , INITCOND = <replaceable class="PARAMETER">initial_condition</replaceable> ] [ , SORTOP = <replaceable class="PARAMETER">sort_operator</replaceable> ] @@ -265,6 +267,22 @@ SELECT col FROM tab ORDER BY col USING sortop LIMIT 1; </varlistentry> <varlistentry> + <term><replaceable class="PARAMETER">state_data_size</replaceable></term> + <listitem> + <para> + The approximate average size (in bytes) of the aggregate's state value. + If this parameter is omitted or is zero, a default estimate is used + based on the <replaceable>state_data_type</>. + The planner uses this value to estimate the memory required for a + grouped aggregate query. The planner will consider using hash + aggregation for such a query only if the hash table is estimated to fit + in <xref linkend="guc-work-mem">; therefore, large values of this + parameter discourage use of hash aggregation. + </para> + </listitem> + </varlistentry> + + <varlistentry> <term><replaceable class="PARAMETER">ffunc</replaceable></term> <listitem> <para> |