| <?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> |