diff options
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/config.sgml | 20 |
1 files changed, 14 insertions, 6 deletions
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index 57cd7bb9727..4e77adc7f17 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -5567,9 +5567,13 @@ ANY <replaceable class="parameter">num_sync</replaceable> ( <replaceable class=" joining the matching partitions. Partitionwise join currently applies only when the join conditions include all the partition keys, which must be of the same data type and have one-to-one matching sets of - child partitions. Because partitionwise join planning can use - significantly more CPU time and memory during planning, the default is - <literal>off</literal>. + child partitions. With this setting enabled, the number of nodes + whose memory usage is restricted by <varname>work_mem</varname> + appearing in the final plan can increase linearly according to the + number of partitions being scanned. This can result in a large + increase in overall memory consumption during the execution of the + query. Query planning also becomes significantly more expensive in + terms of memory and CPU. The default value is <literal>off</literal>. </para> </listitem> </varlistentry> @@ -5587,9 +5591,13 @@ ANY <replaceable class="parameter">num_sync</replaceable> ( <replaceable class=" tables to be performed separately for each partition. If the <literal>GROUP BY</literal> clause does not include the partition keys, only partial aggregation can be performed on a per-partition - basis, and finalization must be performed later. Because - partitionwise grouping or aggregation can use significantly more CPU - time and memory during planning, the default is + basis, and finalization must be performed later. With this setting + enabled, the number of nodes whose memory usage is restricted by + <varname>work_mem</varname> appearing in the final plan can increase + linearly according to the number of partitions being scanned. This + can result in a large increase in overall memory consumption during + the execution of the query. Query planning also becomes significantly + more expensive in terms of memory and CPU. The default value is <literal>off</literal>. </para> </listitem> |