If this parameter is omitted or is zero, a default estimate is used

based on the <replaceable>state_data_type</replaceable>.

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.

grouped aggregate query.

</para>

</listitem>

</varlistentry>