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commit 19b5d781f46798d0ad4fdb4bc8deb352a6d15d07 Author: Shajini Thayasingh <[email protected]> AuthorDate: Wed Mar 8 11:20:23 2023 -0800 IMPALA-11987: [DOCS] Document the mem_limit_executors query option Document the difference between mem_limit and mem_limit_executors query options. Change-Id: Ibce8347d564afde0f9b9e83df560454f4b8b5c9d Reviewed-on: http://gerrit.cloudera.org:8080/19604 Tested-by: Impala Public Jenkins <[email protected]> Reviewed-by: Daniel Becker <[email protected]> Reviewed-by: Wenzhe Zhou <[email protected]> --- docs/topics/impala_mem_limit.xml | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) diff --git a/docs/topics/impala_mem_limit.xml b/docs/topics/impala_mem_limit.xml index aec76e65a..02a1d7750 100644 --- a/docs/topics/impala_mem_limit.xml +++ b/docs/topics/impala_mem_limit.xml @@ -209,5 +209,24 @@ for buffer reservations. Memory reservation needed given the current plan: 38.00 or the pool config (max-query-mem-limit, min-query-mem-limit) for the query to allow the query memory limit to be at least 70.00 MB. Note that changing the mem_limit may also change the plan. See the query profile for more information about the per-node memory requirements.</codeblock> - </conbody> +</conbody> +<concept id="mem_limit_executors"> + <title>MEM_LIMIT_EXECUTORS Query Option</title> + <conbody> + <note>This is a developer-only query option. Setting this query option is not recommended + unless specifically advised.</note> + <p>The existing <codeph>MEM_LIMIT</codeph> query option applies to all impala coordinators and + executors. This means that the same amount of memory gets reserved but coordinators + typically just do the job of coordinating the query and thus do not necessarily need all the + estimated memory. Blocking the estimated memory on coordinators blocks the memory to be used + for other queries.</p> + <p>The new <codeph>MEM_LIMIT_EXECUTORS</codeph> query option functions similarly to the + <codeph>MEM_LIMIT</codeph> option but sets the query memory limit only on executors. This + new option addresses the issue related to <codeph>MEM_LIMIT</codeph> and is recommended in + scenarios where the query needs much higher memory on executors compared with + coordinators.</p> + <p>Note that the <codeph>MEM_LIMIT_EXECUTORS</codeph> option does not work with + <codeph>MEM_LIMIT</codeph>. If you set both, only <codeph>MEM_LIMIT</codeph> applies.</p> + </conbody> +</concept> </concept>
