IMPALA-5937: [DOCS] Documented ENABLE_EXPR_REWRITES query option Change-Id: I82a27172a6a6570f9c3cebe1a516a29c755e6d58 Reviewed-on: http://gerrit.cloudera.org:8080/11206 Tested-by: Impala Public Jenkins <[email protected]> Reviewed-by: Thomas Marshall <[email protected]>
Project: http://git-wip-us.apache.org/repos/asf/impala/repo Commit: http://git-wip-us.apache.org/repos/asf/impala/commit/d1d07f72 Tree: http://git-wip-us.apache.org/repos/asf/impala/tree/d1d07f72 Diff: http://git-wip-us.apache.org/repos/asf/impala/diff/d1d07f72 Branch: refs/heads/master Commit: d1d07f7295ae4d6876097f0f86cb722da63f4caa Parents: df18658 Author: Alex Rodoni <[email protected]> Authored: Mon Aug 13 17:27:26 2018 -0700 Committer: Alex Rodoni <[email protected]> Committed: Thu Aug 23 20:11:31 2018 +0000 ---------------------------------------------------------------------- docs/impala.ditamap | 1 + docs/topics/impala_enable_expr_rewrites.xml | 86 ++++++++++++++++++++++++ 2 files changed, 87 insertions(+) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/impala/blob/d1d07f72/docs/impala.ditamap ---------------------------------------------------------------------- diff --git a/docs/impala.ditamap b/docs/impala.ditamap index 9260a9b..73c5d23 100644 --- a/docs/impala.ditamap +++ b/docs/impala.ditamap @@ -187,6 +187,7 @@ under the License. <topicref rev="2.5.0" href="topics/impala_disable_row_runtime_filtering.xml"/> <topicref rev="2.5.0" href="topics/impala_disable_streaming_preaggregations.xml"/> <topicref href="topics/impala_disable_unsafe_spills.xml"/> + <topicref href="topics/impala_enable_expr_rewrites.xml"/> <topicref href="topics/impala_exec_single_node_rows_threshold.xml"/> <topicref href="topics/impala_exec_time_limit_s.xml"/> <topicref href="topics/impala_explain_level.xml"/> http://git-wip-us.apache.org/repos/asf/impala/blob/d1d07f72/docs/topics/impala_enable_expr_rewrites.xml ---------------------------------------------------------------------- diff --git a/docs/topics/impala_enable_expr_rewrites.xml b/docs/topics/impala_enable_expr_rewrites.xml new file mode 100644 index 0000000..b52914a --- /dev/null +++ b/docs/topics/impala_enable_expr_rewrites.xml @@ -0,0 +1,86 @@ +<?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="enable_expr_rewrites"> + + <title>ENABLE_EXPR_REWRITES Query Option</title> + + <titlealts audience="PDF"> + + <navtitle>ENABLE_EXPR_REWRITES</navtitle> + + </titlealts> + + <prolog> + <metadata> + <data name="Category" value="Impala"/> + <data name="Category" value="Impala Query Options"/> + <data name="Category" value="Troubleshooting"/> + <data name="Category" value="Performance"/> + </metadata> + </prolog> + + <conbody> + + <p> + The <codeph>ENABLE_EXPR_REWRITES</codeph> query option controls whether to enable or + disable the query compile time optimizations that rewrite the expression trees to a more + compact and optimized form that helps avoid redundant expression evaluation at run time. + Performance optimizations controlled by this query option include: + </p> + + <ul> + <li> + Constant folding (added in <keyword keyref="impala28">)</keyword> + </li> + + <li> + Extracting common conjuncts from disjunctions (added in + <keyword + keyref="impala28">)</keyword> + </li> + + <li> + Simplify conditionals with constant conditions (added in + <keyword + keyref="impala29">)</keyword> + </li> + </ul> + + <p> + Set the option to <codeph>false</codeph> or <codeph>0</codeph> to disable the performance + optimizations. + </p> + + <p> + <b>Type: </b><codeph>boolean</codeph> + </p> + + <p> + <b>Default:</b> <codeph>true</codeph> (<codeph>1</codeph>) + </p> + + <p> + <b>Added in:</b> <keyword keyref="impala28"/> + </p> + + </conbody> + +</concept>
