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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> |