Commit121d774

committed

Doc: add information about partition locking

The documentation around locking of partitions for the executor startupphase of run-time partition pruning wasn't clear about which partitionswere being locked. Fix that.Reviewed-by: Tender Wang <tndrwang@gmail.com>Discussion:https://postgr.es/m/CAApHDvp738G75HfkKcfXaf3a8s%3D6mmtOLh46tMD0D2hAo1UCzA%40mail.gmail.comBackpatch-through: 13

1 parentb3219c6 commit121d774Copy full SHA for 121d774

File tree

-1

lines changed

-1

lines changed

Lines changed: 7 additions & 1 deletion

Original file line number	Diff line number	Diff line change
`@@ -5075,7 +5075,13 @@ EXPLAIN SELECT count(*) FROM measurement WHERE logdate >= DATE '2008-01-01';`
`5075`	`5075`	`It is possible to determine the number of partitions which were`
`5076`	`5076`	`removed during this phase by observing the`
`5077`	`5077`	`<quote>Subplans Removed</quote> property in the`
`5078`		`- <command>EXPLAIN</command> output.`
	`5078`	`+ <command>EXPLAIN</command> output. The query planner obtains locks for`
	`5079`	`+ all partitions which are part of the plan. However, when the executor`
	`5080`	`+ uses a cached plan, locks are only obtained on the partitions which`
	`5081`	`+ remain after partition pruning done during the initialization phase of`
	`5082`	`+ execution, i.e., the ones shown in the <command>EXPLAIN</command>`
	`5083`	`+ output and not the ones referred to by the`
	`5084`	`+ <quote>Subplans Removed</quote> property.`
`5079`	`5085`	`</para>`
`5080`	`5086`	`</listitem>`
`5081`	`5087`

Comments

(0)