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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE concept PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
<concept id="broadcast_bytes_limit">
<title>BROADCAST_BYTES_LIMIT Query Option</title>
<titlealts audience="PDF">
<navtitle>BROADCAST BYTES LIMIT</navtitle>
</titlealts>
<prolog>
<metadata>
<data name="Category" value="Impala"/>
<data name="Category" value="Impala Query Options"/>
</metadata>
</prolog>
<conbody>
<p>
<indexterm audience="hidden">BROADCAST_BYTES_LIMIT query option</indexterm> Sets the limit
for the size of the broadcast input based on estimated size.
</p>
<p>
The Impala planner may in rare cases make a bad choice to broadcast a large table or intermediate
result and encounter performance problems due to high memory pressure. Setting this limit will
make the planner pick a partition based hash join instead of broadcast and avoid such performance problems.
</p>
<p conref="../shared/impala_common.xml#common/type_integer"/>
<p conref="../shared/impala_common.xml#common/default_blurb"/>
<p>
The default value is 34359738368 (32 GB). A value of 0 causes the option to be ignored.
</p>
<p conref="../shared/impala_common.xml#common/example_blurb"/>
<codeblock><![CDATA[
-- Change the limit to 16GB.
set broadcast_bytes_limit=17179869184;
-- Disable the BROADCAST_BYTES_LIMIT.
set broadcast_bytes_limit=0;
]]>
</codeblock>
</conbody>
</concept>