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| <!DOCTYPE concept PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd"> |
| <concept id="num_scanner_threads"> |
| |
| <title>NUM_SCANNER_THREADS Query Option</title> |
| <titlealts audience="PDF"><navtitle>NUM_SCANNER_THREADS</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> |
| <indexterm audience="hidden">NUM_SCANNER_THREADS query option</indexterm> |
| Maximum number of scanner threads (on each node) used for each query. By default, Impala uses as many cores |
| as are available (one thread per core). You might lower this value if queries are using excessive resources |
| on a busy cluster. Impala imposes a maximum value automatically, so a high value has no practical effect. |
| </p> |
| |
| <p> |
| <b>Type:</b> numeric |
| </p> |
| |
| <p> |
| <b>Default:</b> 0 |
| </p> |
| |
| </conbody> |
| </concept> |