IMPALA-6867: [DOCS] SHUFFLE_DISTINCT_EXPRS Query option added Change-Id: I42cb22a13b26bdc3d22585e4fc23934dfc91722a Reviewed-on: http://gerrit.cloudera.org:8080/10094 Reviewed-by: Tianyi Wang <[email protected]> Tested-by: Impala Public Jenkins <[email protected]>
Project: http://git-wip-us.apache.org/repos/asf/impala/repo Commit: http://git-wip-us.apache.org/repos/asf/impala/commit/62d33881 Tree: http://git-wip-us.apache.org/repos/asf/impala/tree/62d33881 Diff: http://git-wip-us.apache.org/repos/asf/impala/diff/62d33881 Branch: refs/heads/master Commit: 62d33881b0a122df4284495e88f4266bc97ad353 Parents: 740fc6b Author: Alex Rodoni <[email protected]> Authored: Tue Apr 17 20:04:39 2018 -0700 Committer: Impala Public Jenkins <[email protected]> Committed: Wed Apr 18 20:32:07 2018 +0000 ---------------------------------------------------------------------- docs/impala.ditamap | 1 + docs/impala_keydefs.ditamap | 1 + docs/topics/impala_shuffle_distinct_exprs.xml | 59 ++++++++++++++++++++++ 3 files changed, 61 insertions(+) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/impala/blob/62d33881/docs/impala.ditamap ---------------------------------------------------------------------- diff --git a/docs/impala.ditamap b/docs/impala.ditamap index 4e9c71a..f40ae8f 100644 --- a/docs/impala.ditamap +++ b/docs/impala.ditamap @@ -220,6 +220,7 @@ under the License. <topicref rev="2.8.0 IMPALA-3671" href="topics/impala_scratch_limit.xml"/> <!-- This option is for internal use only and might go away without ever being documented. --> <!-- <topicref href="topics/impala_seq_compression_mode.xml"/> --> + <topicref href="topics/impala_shuffle_distinct_exprs.xml"/> <topicref href="topics/impala_support_start_over.xml"/> <topicref href="topics/impala_sync_ddl.xml"/> </topicref> http://git-wip-us.apache.org/repos/asf/impala/blob/62d33881/docs/impala_keydefs.ditamap ---------------------------------------------------------------------- diff --git a/docs/impala_keydefs.ditamap b/docs/impala_keydefs.ditamap index 52b86cf..e94fe5d 100644 --- a/docs/impala_keydefs.ditamap +++ b/docs/impala_keydefs.ditamap @@ -10818,6 +10818,7 @@ under the License. <keydef href="topics/impala_runtime_filter_wait_time_ms.xml" keys="runtime_filter_wait_time_ms"/> <keydef href="topics/impala_s3_skip_insert_staging.xml" keys="s3_skip_insert_staging"/> <keydef href="topics/impala_scratch_limit.xml" keys="scratch_limit"/> + <keydef href="topics/impala_shuffle_distinct_exprs.xml" keys="shuffle_distinct_exprs"/> <keydef href="topics/impala_support_start_over.xml" keys="support_start_over"/> <keydef href="topics/impala_sync_ddl.xml" keys="sync_ddl"/> http://git-wip-us.apache.org/repos/asf/impala/blob/62d33881/docs/topics/impala_shuffle_distinct_exprs.xml ---------------------------------------------------------------------- diff --git a/docs/topics/impala_shuffle_distinct_exprs.xml b/docs/topics/impala_shuffle_distinct_exprs.xml new file mode 100644 index 0000000..804ca4f --- /dev/null +++ b/docs/topics/impala_shuffle_distinct_exprs.xml @@ -0,0 +1,59 @@ +<?xml version="1.0" encoding="UTF-8"?> +<!-- +Licensed to the Apache Software Foundation (ASF) under one +or more contributor license agreements. See the NOTICE file +distributed with this work for additional information +regarding copyright ownership. The ASF licenses this file +to you under the Apache License, Version 2.0 (the +"License"); you may not use this file except in compliance +with the License. You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + +Unless required by applicable law or agreed to in writing, +software distributed under the License is distributed on an +"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +KIND, either express or implied. See the License for the +specific language governing permissions and limitations +under the License. +--> +<!DOCTYPE concept PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd"> +<concept id="shuffle_distinct_exprs"> + + <title>SHUFFLE_DISTINCT_EXPRS Query Option</title> + + <titlealts audience="PDF"> + + <navtitle>SHUFFLE_DISTINCT_EXPRS</navtitle> + + </titlealts> + + <prolog> + <metadata> + <data name="Category" value="Impala"/> + <data name="Category" value="Impala Query Options"/> + </metadata> + </prolog> + + <conbody> + + <p> + The <codeph>SHUFFLE_DISTINCT_EXPRS</codeph> query option controls the + shuffling behavior when a query has both grouping and distinct expressions. + Impala can optionally include the distinct expressions in the hash exchange + to spread the data among more nodes. However, this plan requires one more + hash exchange phase. + </p> + + <p> + It is recommended that you turn off this option if the NDVs of the grouping + expressions are high. + </p> + + <p conref="../shared/impala_common.xml#common/type_boolean"/> + + <p conref="../shared/impala_common.xml#common/default_false"/> + + </conbody> + +</concept>
