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<!DOCTYPE concept PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
<concept id="large_agg_mem_threshold" rev="4.4.0">
<title>LARGE_AGG_MEM_THRESHOLD Query Option (<keyword keyref="impala44"/> or higher only)</title>
<titlealts audience="PDF">
<navtitle>LARGE AGG MEM 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="4.4.0">
<indexterm audience="hidden">LARGE_AGG_MEM_THRESHOLD query option</indexterm>
The threshold for the query planner to determine whether memory estimation for an
aggregation node is large or not. Together with <codeph>AGG_MEM_CORRELATION_FACTOR</codeph>,
the planner will use this value to lower memory estimation for a large aggregation node.
</p>
<p>
Users can set this option value to 0.0 so the planner stays using the default
NDV multiplication based-estimation. See <codeph>AGG_MEM_CORRELATION_FACTOR</codeph>
documentation for more detail.
</p>
<p conref="../shared/impala_common.xml#common/type_integer"/>
<p conref="../shared/impala_common.xml#common/default_blurb"/>
<p>
<codeph>536870912</codeph> (512 MB)
</p>
<p conref="../shared/impala_common.xml#common/units_blurb"/>
<p conref="../shared/impala_common.xml#common/added_in_440"/>
<p conref="../shared/impala_common.xml#common/related_info"/>
<p>
<xref href="impala_agg_mem_correlation_factor.xml"/>
</p>
</conbody>
</concept>