IMPALA-7836: [DOCS] Format changes in impala_topn_bytes_limit.xml Change-Id: I731b26fe2c225e706454f16cd3b6de697ec70fe2 Reviewed-on: http://gerrit.cloudera.org:8080/11935 Reviewed-by: Alex Rodoni <[email protected]> Tested-by: Impala Public Jenkins <[email protected]> (cherry picked from commit 3dea93ef0f364325dff2893642d5516a4ecd16bd)
Project: http://git-wip-us.apache.org/repos/asf/impala/repo Commit: http://git-wip-us.apache.org/repos/asf/impala/commit/f5348d4c Tree: http://git-wip-us.apache.org/repos/asf/impala/tree/f5348d4c Diff: http://git-wip-us.apache.org/repos/asf/impala/diff/f5348d4c Branch: refs/heads/branch-3.1.0 Commit: f5348d4cd88fff23b118dfef68db978e54327c15 Parents: bd573d1 Author: Alex Rodoni <[email protected]> Authored: Thu Nov 15 13:18:33 2018 -0800 Committer: Zoltan Borok-Nagy <[email protected]> Committed: Tue Nov 27 11:59:20 2018 +0100 ---------------------------------------------------------------------- docs/topics/impala_topn_bytes_limit.xml | 19 +++++++++---------- 1 file changed, 9 insertions(+), 10 deletions(-) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/impala/blob/f5348d4c/docs/topics/impala_topn_bytes_limit.xml ---------------------------------------------------------------------- diff --git a/docs/topics/impala_topn_bytes_limit.xml b/docs/topics/impala_topn_bytes_limit.xml index c6329f9..fa212b2 100644 --- a/docs/topics/impala_topn_bytes_limit.xml +++ b/docs/topics/impala_topn_bytes_limit.xml @@ -42,19 +42,18 @@ under the License. <p> The <codeph>TOPN_BYTES_LIMIT</codeph> query option places a limit on the amount of - estimated memory that Impala can process for <term>top-N</term> queries. + estimated memory that Impala can process for <i>top-N</i> queries. </p> <p> - <term>top-N</term> queries are the queries that include both <codeph>ORDER BY</codeph> and - <codeph>LIMIT</codeph> clauses. <term>top-N</term> queries don't spill to disk so they - have to keep all rows they process in memory, and those queries can cause out-of-memory - issues when running with a large limit and an offset. If the Impala planner estimates that - a <term>top-N</term> operator will process more bytes than the - <codeph>TOPN_BYTES_LIMIT</codeph> value, it will replace the <term>top-N</term> operator - with the <term>sort</term> operator. Switching to the <term>sort</term> operator allows - Impala to spill to disk, thus requiring less memory than <term>top-N</term>, but - potentially with performance penalties. + <i>Top-N</i> queries are the queries that include both <codeph>ORDER BY</codeph> and + <codeph>LIMIT</codeph> clauses. <i>Top-N</i> queries don't spill to disk so they have to + keep all rows they process in memory, and those queries can cause out-of-memory issues + when running with a large limit and an offset. If the Impala planner estimates that a + <i>top-N</i> operator will process more bytes than the <codeph>TOPN_BYTES_LIMIT</codeph> + value, it will replace the <i>top-N</i> operator with the <i>sort</i> operator. Switching + to the <i>sort</i> operator allows Impala to spill to disk, thus requiring less memory + than <i>top-N</i>, but potentially with performance penalties. </p> <p>
