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Posted to commits@impala.apache.org by jo...@apache.org on 2019/10/16 03:25:46 UTC
[impala] 01/03: IMPALA-8920: [DOCS] Documented the query option for
disabling HBase row estimation
This is an automated email from the ASF dual-hosted git repository.
joemcdonnell pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/impala.git
commit 2d74dfd5e2bf4791c116e14911631715c0db3a86
Author: Alex Rodoni <ar...@cloudera.com>
AuthorDate: Tue Oct 8 17:03:56 2019 -0700
IMPALA-8920: [DOCS] Documented the query option for disabling HBase row estimation
Change-Id: Id131b66a3457ef6cbc326a0f3ed99de2a3950c3e
Reviewed-on: http://gerrit.cloudera.org:8080/14394
Tested-by: Impala Public Jenkins <im...@cloudera.com>
Reviewed-by: Quanlong Huang <hu...@gmail.com>
---
docs/impala.ditamap | 2 +-
docs/impala_keydefs.ditamap | 1 -
.../impala_disable_hbase_num_rows_estimate.xml | 89 ++++++++++++++++++++++
docs/topics/impala_disable_outermost_topn.xml | 47 ------------
4 files changed, 90 insertions(+), 49 deletions(-)
diff --git a/docs/impala.ditamap b/docs/impala.ditamap
index be4b76b..8e11b89 100644
--- a/docs/impala.ditamap
+++ b/docs/impala.ditamap
@@ -186,7 +186,7 @@ under the License.
<topicref rev="3.3.0" href="topics/impala_default_transactional_type.xml"/>
<topicref href="topics/impala_disable_codegen.xml"/>
<topicref rev="2.10.0 IMPALA-5483" href="topics/impala_disable_codegen_rows_threshold.xml"/>
- <topicref audience="hidden" href="topics/impala_disable_outermost_topn.xml"/>
+ <topicref href="topics/impala_disable_hbase_num_rows_estimate.xml"/>
<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"/>
diff --git a/docs/impala_keydefs.ditamap b/docs/impala_keydefs.ditamap
index c71bdf2..efb6f5f 100644
--- a/docs/impala_keydefs.ditamap
+++ b/docs/impala_keydefs.ditamap
@@ -10790,7 +10790,6 @@ under the License.
<keydef rev="2.10.0 IMPALA-3200" href="topics/impala_default_spillable_buffer_size.xml" keys="default_spillable_buffer_size"/>
<keydef href="topics/impala_disable_codegen.xml" keys="disable_codegen"/>
<keydef href="topics/impala_disable_codegen_rows_threshold.xml" keys="disable_codegen_rows_threshold"/>
- <keydef href="topics/impala_disable_outermost_topn.xml" keys="disable_outermost_topn"/>
<keydef href="topics/impala_disable_row_runtime_filtering.xml" keys="disable_row_runtime_filtering"/>
<keydef href="topics/impala_disable_streaming_preaggregations.xml" keys="disable_streaming_preaggregations"/>
<keydef href="topics/impala_disable_unsafe_spills.xml" keys="disable_unsafe_spills"/>
diff --git a/docs/topics/impala_disable_hbase_num_rows_estimate.xml b/docs/topics/impala_disable_hbase_num_rows_estimate.xml
new file mode 100644
index 0000000..998d551
--- /dev/null
+++ b/docs/topics/impala_disable_hbase_num_rows_estimate.xml
@@ -0,0 +1,89 @@
+<?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="disable_hbase_num_rows_estimate">
+
+ <title>DISABLE_HBASE_NUM_ROWS_ESTIMATE Query Option</title>
+
+ <titlealts audience="PDF">
+
+ <navtitle>DISABLE_HBASE_NUM_ROWS_ESTIMATE</navtitle>
+
+ </titlealts>
+
+ <prolog>
+ <metadata>
+ <data name="Category" value="Impala"/>
+ <data name="Category" value="Impala Query Options"/>
+ <data name="Category" value="Performance"/>
+ </metadata>
+ </prolog>
+
+ <conbody>
+
+ <p>
+ Use the <codeph>DISABLE_HBASE_NUM_ROWS_ESTIMATE</codeph> query option to disable key
+ sampling of HBase tables in row count and row size estimation.
+ </p>
+
+ <p>
+ While generating a plan for an HBase query, the planner samples the underlying HBase
+ tables to estimate their row count and row size, and the sampling can negatively impact
+ the planning time. When the HBase table stats does not change much in short time, disable
+ the sampling by setting the <codeph>DISABLE_HBASE_NUM_ROWS_ESTIMATE</codeph> query option
+ to <codeph>TRUE</codeph>. And Impala planner will fall back to using Hive Metastore (HMS)
+ table stats instead.
+ </p>
+
+ <p>
+ When <codeph>DISABLE_HBASE_NUM_ROWS_ESTIMATE</codeph> query option is set to
+ <codeph>TRUE</codeph>, you need to update the HMS table stats by running <codeph>COMPUTE
+ STATS</codeph>. Alternatively, you can manually set table statistics by running
+ <codeph>ALTER TABLE</codeph>. See <xref
+ href="impala_perf_stats.xml#perf_stats"/>
+ for details.
+ </p>
+
+ <p>
+ The following values are supported:
+ <ul>
+ <li>
+ <codeph>TRUE</codeph> or <codeph>1</codeph>: Disables the normal key sampling of HBase
+ tables and uses HMS table stats for estimation.
+ </li>
+
+ <li>
+ <codeph>FALSE</codeph> or <codeph>0</codeph>: Enables the normal sampling of HBase
+ tables.
+ </li>
+ </ul>
+ </p>
+
+ <p>
+ <b>Type:</b> <codeph>BOOLEAN</codeph>
+ </p>
+
+ <p>
+ <b>Default:</b> <codeph>FALSE</codeph>
+ </p>
+
+ </conbody>
+
+</concept>
diff --git a/docs/topics/impala_disable_outermost_topn.xml b/docs/topics/impala_disable_outermost_topn.xml
deleted file mode 100644
index 2bc1f12..0000000
--- a/docs/topics/impala_disable_outermost_topn.xml
+++ /dev/null
@@ -1,47 +0,0 @@
-<?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="disable_outermost_topn" rev="2.5.0">
-
- <title>DISABLE_OUTERMOST_TOPN Query Option</title>
- <prolog>
- <metadata>
- <data name="Category" value="Impala"/>
- <data name="Category" value="Impala Query Options"/>
- <data name="Category" value="Developers"/>
- <data name="Category" value="Data Analysts"/>
- </metadata>
- </prolog>
-
- <conbody>
-
- <p rev="2.5.0">
- <indexterm audience="hidden">DISABLE_OUTERMOST_TOPN query option</indexterm>
- </p>
-
- <p>
- <b>Type:</b>
- </p>
-
- <p>
- <b>Default:</b>
- </p>
- </conbody>
-</concept>