IMPALA-6463: [DOCS] Removed query options were deleted from docs

The following query option docs and references were removed from docs:
- DEFAULT_ORDER_BY_LIMIT
- ABORT_ON_DEFAULT_LIMIT_EXCEEDED
- V_CPU_CORES (previously removed)
- RESERVATION_REQUEST_TIMEOUT (previously removed)
- RM_INITIAL_MEM
- SCAN_NODE_CODEGEN_THRESHOLD
- MAX_IO_BUFFERS
- DISABLE_CACHED_READS

Change-Id: I71be3f872468cb22583f82c2238bf72dc82cb750
Cherry-picks: not for 2.x.
Reviewed-on: http://gerrit.cloudera.org:8080/10055
Reviewed-by: Tim Armstrong <tarmstr...@cloudera.com>
Tested-by: Impala Public Jenkins <impala-public-jenk...@cloudera.com>


Project: http://git-wip-us.apache.org/repos/asf/impala/repo
Commit: http://git-wip-us.apache.org/repos/asf/impala/commit/b4228dfd
Tree: http://git-wip-us.apache.org/repos/asf/impala/tree/b4228dfd
Diff: http://git-wip-us.apache.org/repos/asf/impala/diff/b4228dfd

Branch: refs/heads/master
Commit: b4228dfd14975059b2aac68792e63007b5c4e1e2
Parents: d481cd4
Author: Alex Rodoni <arod...@cloudera.com>
Authored: Thu Apr 12 16:31:32 2018 -0700
Committer: Impala Public Jenkins <impala-public-jenk...@cloudera.com>
Committed: Sat Apr 14 00:28:46 2018 +0000

----------------------------------------------------------------------
 docs/impala.ditamap                             |  6 --
 docs/impala_keydefs.ditamap                     |  6 --
 .../impala_abort_on_default_limit_exceeded.xml  | 41 ---------
 docs/topics/impala_default_order_by_limit.xml   | 55 ------------
 docs/topics/impala_disable_cached_reads.xml     | 54 ------------
 docs/topics/impala_max_io_buffers.xml           | 49 -----------
 docs/topics/impala_order_by.xml                 |  9 --
 docs/topics/impala_rm_initial_mem.xml           | 47 ----------
 .../impala_scan_node_codegen_threshold.xml      | 93 --------------------
 9 files changed, 360 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/impala/blob/b4228dfd/docs/impala.ditamap
----------------------------------------------------------------------
diff --git a/docs/impala.ditamap b/docs/impala.ditamap
index 89d9553..e6c9c09 100644
--- a/docs/impala.ditamap
+++ b/docs/impala.ditamap
@@ -170,7 +170,6 @@ under the License.
       </topicref>
       <topicref href="topics/impala_set.xml">
         <topicref href="topics/impala_query_options.xml">
-          <topicref href="topics/impala_abort_on_default_limit_exceeded.xml"/>
           <topicref href="topics/impala_abort_on_error.xml"/>
           <topicref href="topics/impala_allow_unsupported_formats.xml"/>
           <topicref href="topics/impala_appx_count_distinct.xml"/>
@@ -180,9 +179,7 @@ under the License.
           <topicref href="topics/impala_debug_action.xml"/>
           <topicref rev="2.9.0" href="topics/impala_decimal_v2.xml"/>
           <topicref rev="2.9.0 IMPALA-5381" 
href="topics/impala_default_join_distribution_mode.xml"/>
-          <topicref href="topics/impala_default_order_by_limit.xml"/>
           <topicref rev="2.10.0 IMPALA-3200" 
href="topics/impala_default_spillable_buffer_size.xml"/>
-          <topicref audience="hidden" 
href="topics/impala_disable_cached_reads.xml"/>
           <topicref href="topics/impala_disable_codegen.xml"/>
           <topicref audience="hidden" 
href="topics/impala_disable_outermost_topn.xml"/>
           <topicref rev="2.5.0" 
href="topics/impala_disable_row_runtime_filtering.xml"/>
@@ -195,7 +192,6 @@ under the License.
           <topicref href="topics/impala_live_progress.xml"/>
           <topicref href="topics/impala_live_summary.xml"/>
           <topicref href="topics/impala_max_errors.xml"/>
-          <topicref href="topics/impala_max_io_buffers.xml"/>
           <topicref rev="2.10.0 IMPALA-3200" 
href="topics/impala_max_row_size.xml"/>
           <topicref rev="2.5.0" 
href="topics/impala_max_num_runtime_filters.xml"/>
           <topicref href="topics/impala_max_scan_range_length.xml"/>
@@ -214,14 +210,12 @@ under the License.
           <topicref href="topics/impala_query_timeout_s.xml"/>
           <topicref href="topics/impala_request_pool.xml"/>
           <topicref rev="2.7.0" href="topics/impala_replica_preference.xml"/>
-          <topicref audience="hidden" href="topics/impala_rm_initial_mem.xml"/>
           <topicref rev="2.5.0" 
href="topics/impala_runtime_bloom_filter_size.xml"/>
           <topicref rev="2.6.0" 
href="topics/impala_runtime_filter_max_size.xml"/>
           <topicref rev="2.6.0" 
href="topics/impala_runtime_filter_min_size.xml"/>
           <topicref rev="2.5.0" href="topics/impala_runtime_filter_mode.xml"/>
           <topicref rev="2.5.0" 
href="topics/impala_runtime_filter_wait_time_ms.xml"/>
           <topicref rev="2.6.0" 
href="topics/impala_s3_skip_insert_staging.xml"/>
-          <topicref rev="2.5.0" 
href="topics/impala_scan_node_codegen_threshold.xml"/>
           <topicref rev="2.5.0" 
href="topics/impala_schedule_random_replica.xml"/>
           <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. -->

http://git-wip-us.apache.org/repos/asf/impala/blob/b4228dfd/docs/impala_keydefs.ditamap
----------------------------------------------------------------------
diff --git a/docs/impala_keydefs.ditamap b/docs/impala_keydefs.ditamap
index be64501..0a2ac82 100644
--- a/docs/impala_keydefs.ditamap
+++ b/docs/impala_keydefs.ditamap
@@ -10768,7 +10768,6 @@ under the License.
   <keydef href="topics/impala_hints.xml" keys="hints"/>
   <keydef href="topics/impala_set.xml" keys="set"/>
   <keydef href="topics/impala_query_options.xml" keys="query_options"/>
-  <keydef href="topics/impala_abort_on_default_limit_exceeded.xml" 
keys="abort_on_default_limit_exceeded"/>
   <keydef href="topics/impala_abort_on_error.xml" keys="abort_on_error"/>
   <keydef href="topics/impala_allow_unsupported_formats.xml" 
keys="allow_unsupported_formats"/>
   <keydef href="topics/impala_appx_count_distinct.xml" 
keys="appx_count_distinct"/>
@@ -10777,9 +10776,7 @@ under the License.
   <keydef href="topics/impala_compression_codec.xml" keys="compression_codec"/>
   <keydef href="topics/impala_debug_action.xml" keys="debug_action"/>
   <keydef href="topics/impala_default_join_distribution_mode.xml" 
keys="default_join_distribution_mode"/>
-  <keydef href="topics/impala_default_order_by_limit.xml" 
keys="default_order_by_limit"/>
   <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_cached_reads.xml" 
keys="disable_cached_reads"/>
   <keydef href="topics/impala_disable_codegen.xml" keys="disable_codegen"/>
   <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"/>
@@ -10792,7 +10789,6 @@ under the License.
   <keydef href="topics/impala_live_progress.xml" keys="live_progress"/>
   <keydef href="topics/impala_live_summary.xml" keys="live_summary"/>
   <keydef href="topics/impala_max_errors.xml" keys="max_errors"/>
-  <keydef href="topics/impala_max_io_buffers.xml" keys="max_io_buffers"/>
   <keydef rev="2.10.0 IMPALA-3200" href="topics/impala_max_row_size.xml" 
keys="max_row_size"/>
   <keydef href="topics/impala_max_scan_range_length.xml" 
keys="max_scan_range_length"/>
   <keydef href="topics/impala_max_num_runtime_filters.xml" 
keys="max_num_runtime_filters"/>
@@ -10812,14 +10808,12 @@ under the License.
   <keydef href="topics/impala_request_pool.xml" keys="request_pool"/>
   <keydef href="topics/impala_schedule_random_replica.xml" 
keys="schedule_random_replica"/>
   <keydef href="topics/impala_replica_preference.xml" 
keys="replica_preference"/>
-  <keydef href="topics/impala_rm_initial_mem.xml" keys="rm_initial_mem"/>
   <keydef href="topics/impala_runtime_bloom_filter_size.xml" 
keys="runtime_bloom_filter_size"/>
   <keydef href="topics/impala_runtime_filter_max_size.xml" 
keys="runtime_filter_max_size"/>
   <keydef href="topics/impala_runtime_filter_min_size.xml" 
keys="runtime_filter_min_size"/>
   <keydef href="topics/impala_runtime_filter_mode.xml" 
keys="runtime_filter_mode"/>
   <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_scan_node_codegen_threshold.xml" 
keys="scan_node_codegen_threshold"/>
   <keydef href="topics/impala_scratch_limit.xml" keys="scratch_limit"/>
   <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/b4228dfd/docs/topics/impala_abort_on_default_limit_exceeded.xml
----------------------------------------------------------------------
diff --git a/docs/topics/impala_abort_on_default_limit_exceeded.xml 
b/docs/topics/impala_abort_on_default_limit_exceeded.xml
deleted file mode 100644
index ec6973b..0000000
--- a/docs/topics/impala_abort_on_default_limit_exceeded.xml
+++ /dev/null
@@ -1,41 +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 rev="obwl" id="abort_on_default_limit_exceeded">
-
-  <title>ABORT_ON_DEFAULT_LIMIT_EXCEEDED Query Option</title>
-  <titlealts 
audience="PDF"><navtitle>ABORT_ON_DEFAULT_LIMIT_EXCEEDED</navtitle></titlealts>
-  <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 conref="../shared/impala_common.xml#common/obwl_query_options"/>
-
-    <p conref="../shared/impala_common.xml#common/type_boolean"/>
-    <p conref="../shared/impala_common.xml#common/default_false_0"/>
-  </conbody>
-</concept>

http://git-wip-us.apache.org/repos/asf/impala/blob/b4228dfd/docs/topics/impala_default_order_by_limit.xml
----------------------------------------------------------------------
diff --git a/docs/topics/impala_default_order_by_limit.xml 
b/docs/topics/impala_default_order_by_limit.xml
deleted file mode 100644
index 5c72126..0000000
--- a/docs/topics/impala_default_order_by_limit.xml
+++ /dev/null
@@ -1,55 +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 rev="obwl" id="default_order_by_limit">
-
-  <title>DEFAULT_ORDER_BY_LIMIT Query Option</title>
-  <titlealts 
audience="PDF"><navtitle>DEFAULT_ORDER_BY_LIMIT</navtitle></titlealts>
-  <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 conref="../shared/impala_common.xml#common/obwl_query_options"/>
-
-    <p rev="1.4.0">
-      Prior to Impala 1.4.0, Impala queries that use the <codeph><xref 
href="impala_order_by.xml#order_by">ORDER
-      BY</xref></codeph> clause must also include a
-      <codeph><xref href="impala_limit.xml#limit">LIMIT</xref></codeph> 
clause, to avoid accidentally producing
-      huge result sets that must be sorted. Sorting a huge result set is a 
memory-intensive operation. In Impala
-      1.4.0 and higher, Impala uses a temporary disk work area to perform the 
sort if that operation would
-      otherwise exceed the Impala memory limit on a particular host.
-    </p>
-
-    <p>
-      <b>Type: numeric</b>
-    </p>
-
-    <p>
-      <b>Default:</b> -1 (no default limit)
-    </p>
-  </conbody>
-</concept>

http://git-wip-us.apache.org/repos/asf/impala/blob/b4228dfd/docs/topics/impala_disable_cached_reads.xml
----------------------------------------------------------------------
diff --git a/docs/topics/impala_disable_cached_reads.xml 
b/docs/topics/impala_disable_cached_reads.xml
deleted file mode 100644
index 20391db..0000000
--- a/docs/topics/impala_disable_cached_reads.xml
+++ /dev/null
@@ -1,54 +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_cached_reads" rev="1.4.0">
-
-  <title>DISABLE_CACHED_READS Query Option</title>
-  <prolog>
-    <metadata>
-      <data name="Category" value="Impala"/>
-      <data name="Category" value="Impala Query Options"/>
-      <data name="Category" value="HDFS"/>
-      <data name="Category" value="HDFS Caching"/>
-      <data name="Category" value="Querying"/>
-      <data name="Category" value="Performance"/>
-      <data name="Category" value="Developers"/>
-      <data name="Category" value="Data Analysts"/>
-    </metadata>
-  </prolog>
-
-  <conbody>
-
-    <p>
-      <indexterm audience="hidden">DISABLE_CACHED_READS query 
option</indexterm>
-      Prevents Impala from reading data files that are <q>pinned</q> in memory
-      through the HDFS caching feature. Primarily a debugging option for
-      cases where processing of HDFS cached data is concentrated on a single
-      host, leading to excessive CPU usage on that host.
-    </p>
-
-    <p conref="../shared/impala_common.xml#common/type_boolean"/>
-
-    <p conref="../shared/impala_common.xml#common/default_false"/>
-
-    <p conref="../shared/impala_common.xml#common/added_in_140"/>
-
-  </conbody>
-</concept>

http://git-wip-us.apache.org/repos/asf/impala/blob/b4228dfd/docs/topics/impala_max_io_buffers.xml
----------------------------------------------------------------------
diff --git a/docs/topics/impala_max_io_buffers.xml 
b/docs/topics/impala_max_io_buffers.xml
deleted file mode 100644
index 747b4d9..0000000
--- a/docs/topics/impala_max_io_buffers.xml
+++ /dev/null
@@ -1,49 +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="max_io_buffers">
-
-  <title>MAX_IO_BUFFERS Query Option</title>
-  <titlealts audience="PDF"><navtitle>MAX_IO_BUFFERS</navtitle></titlealts>
-  <prolog>
-    <metadata>
-      <data name="Category" value="Impala"/>
-      <data name="Category" value="Impala Query Options"/>
-      <data name="Category" value="Deprecated Features"/>
-      <data name="Category" value="Developers"/>
-      <data name="Category" value="Data Analysts"/>
-    </metadata>
-  </prolog>
-
-  <conbody>
-
-    <p>
-      Deprecated query option. Currently has no effect.
-    </p>
-
-    <p>
-      <b>Type:</b> numeric
-    </p>
-
-    <p>
-      <b>Default:</b> 0
-    </p>
-  </conbody>
-</concept>

http://git-wip-us.apache.org/repos/asf/impala/blob/b4228dfd/docs/topics/impala_order_by.xml
----------------------------------------------------------------------
diff --git a/docs/topics/impala_order_by.xml b/docs/topics/impala_order_by.xml
index 1c5ac98..a72f74e 100644
--- a/docs/topics/impala_order_by.xml
+++ b/docs/topics/impala_order_by.xml
@@ -265,15 +265,6 @@ SELECT page_title AS "Page 3 of search results", page_url 
FROM search_content
         </p>
       </li>
 
-      <li>
-        <p>
-          The query options
-          <xref 
href="impala_default_order_by_limit.xml#default_order_by_limit">DEFAULT_ORDER_BY_LIMIT</xref>
 and
-          <xref 
href="impala_abort_on_default_limit_exceeded.xml#abort_on_default_limit_exceeded">ABORT_ON_DEFAULT_LIMIT_EXCEEDED</xref>,
-          which formerly controlled the behavior of <codeph>ORDER BY</codeph> 
queries with no limit specified, are
-          now ignored.
-        </p>
-      </li>
     </ul>
 
     <p rev="obwl" 
conref="../shared/impala_common.xml#common/null_sorting_change"/>

http://git-wip-us.apache.org/repos/asf/impala/blob/b4228dfd/docs/topics/impala_rm_initial_mem.xml
----------------------------------------------------------------------
diff --git a/docs/topics/impala_rm_initial_mem.xml 
b/docs/topics/impala_rm_initial_mem.xml
deleted file mode 100644
index fd9f819..0000000
--- a/docs/topics/impala_rm_initial_mem.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="rm_initial_mem" rev="2.5.0">
-
-  <title>RM_INITIAL_MEM 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">RM_INITIAL_MEM query option</indexterm>
-    </p>
-
-    <p>
-      <b>Type:</b>
-    </p>
-
-    <p>
-      <b>Default:</b>
-    </p>
-  </conbody>
-</concept>

http://git-wip-us.apache.org/repos/asf/impala/blob/b4228dfd/docs/topics/impala_scan_node_codegen_threshold.xml
----------------------------------------------------------------------
diff --git a/docs/topics/impala_scan_node_codegen_threshold.xml 
b/docs/topics/impala_scan_node_codegen_threshold.xml
deleted file mode 100644
index 40d1bc6..0000000
--- a/docs/topics/impala_scan_node_codegen_threshold.xml
+++ /dev/null
@@ -1,93 +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="scan_node_codegen_threshold" rev="2.5.0 IMPALA-1755">
-
-  <title>SCAN_NODE_CODEGEN_THRESHOLD Query Option (<keyword 
keyref="impala25"/> or higher only)</title>
-  <titlealts 
audience="PDF"><navtitle>SCAN_NODE_CODEGEN_THRESHOLD</navtitle></titlealts>
-  <prolog>
-    <metadata>
-      <data name="Category" value="Impala"/>
-      <data name="Category" value="Impala Query Options"/>
-      <data name="Category" value="Performance"/>
-      <data name="Category" value="Developers"/>
-      <data name="Category" value="Data Analysts"/>
-    </metadata>
-  </prolog>
-
-  <conbody>
-
-    <p rev="2.5.0 IMPALA-1755">
-      <indexterm audience="hidden">SCAN_NODE_CODEGEN_THRESHOLD query 
option</indexterm>
-      The <codeph>SCAN_NODE_CODEGEN_THRESHOLD</codeph> query option
-      adjusts the aggressiveness of the code generation optimization process
-      when performing I/O read operations. It can help to work around 
performance problems
-      for queries where the table is small and the <codeph>WHERE</codeph> 
clause is complicated.
-    </p>
-
-    <p conref="../shared/impala_common.xml#common/type_integer"/>
-
-    <p>
-      <b>Default:</b> 1800000 (1.8 million)
-    </p>
-
-    <p conref="../shared/impala_common.xml#common/added_in_250"/>
-
-    <p conref="../shared/impala_common.xml#common/usage_notes_blurb"/>
-
-    <p>
-      This query option is intended mainly for the case where a query with a 
very complicated
-      <codeph>WHERE</codeph> clause, such as an <codeph>IN</codeph> operator 
with thousands
-      of entries, is run against a small table, especially a small table using 
Parquet format.
-      The code generation phase can become the dominant factor in the query 
response time,
-      making the query take several seconds even though there is relatively 
little work to do.
-      In this case, increase the value of this option to a much larger amount, 
anything up to
-      the maximum for a 32-bit integer.
-    </p>
-
-    <p>
-      Because this option only affects the code generation phase for the 
portion of the
-      query that performs I/O (the <term>scan nodes</term> within the query 
plan), it
-      lets you continue to keep code generation enabled for other queries, and 
other parts
-      of the same query, that can benefit from it. In contrast, the
-      <codeph>IMPALA_DISABLE_CODEGEN</codeph> query option turns off code 
generation entirely.
-    </p>
-
-    <p>
-      Because of the way the work for queries is divided internally, this 
option might not
-      affect code generation for all kinds of queries. If a plan fragment 
contains a scan
-      node and some other kind of plan node, code generation still occurs 
regardless of
-      this option setting.
-    </p>
-
-    <p>
-      To use this option effectively, you should be familiar with reading 
query profile output
-      to determine the proportion of time spent in the code generation phase, 
and whether
-      code generation is enabled or not for specific plan fragments.
-    </p>
-
-<!--
-    <p conref="../shared/impala_common.xml#common/related_info"/>
-    <p>
-    </p>
--->
-
-  </conbody>
-</concept>

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