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| <!DOCTYPE concept PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd"> |
| <concept id="FETCH_ROWS_TIMEOUT_MS"> |
| <title>FETCH_ROWS_TIMEOUT_MS Query Option</title> |
| <titlealts audience="PDF"> |
| <navtitle>FETCH_ROWS_TIMEOUT_MS</navtitle> |
| </titlealts> |
| <prolog> |
| <metadata> |
| <data name="Category" value="Impala"/> |
| <data name="Category" value="Impala Query Options"/> |
| <data name="Category" value="Querying"/> |
| <data name="Category" value="Developers"/> |
| <data name="Category" value="Data Analysts"/> |
| </metadata> |
| </prolog> |
| <conbody> |
| <p>Use the <codeph>FETCH_ROWS_TIMEOUT_MS</codeph> query option to control |
| how long Impala waits for query results when clients fetch rows.</p> |
| <p> When this query option is set to <codeph>0</codeph>, fetch requests wait |
| indefinitely.</p> |
| <p>The timeout applies both when query result spooling is enabled and disabled:<ul> |
| <li>When result spooling is disabled (<codeph>SPOOL_QUERY_RESULTS = |
| FALSE</codeph>), the timeout controls how long a client waits for a |
| single row batch to be produced by the coordinator. </li> |
| <li>When result spooling is enabled ( (<codeph>SPOOL_QUERY_RESULTS = |
| TRUE</codeph>), a client can fetch multiple row batches at a time, |
| so this timeout controls the total time a client waits for row batches |
| to be produced.</li> |
| </ul></p> |
| <p>The timeout also applies to fetch requests issued against queries in the |
| 'RUNNING' state. A 'RUNNING' query has no rows available, so any fetch |
| request will wait until the query transitions to the 'FINISHED' state and |
| for it to fetch all requested rows. A query in the 'FINISHED' state means |
| that the rows are available to be fetched.</p> |
| <p><b>Type:</b> |
| <codeph>INT</codeph></p> |
| <p><b>Default:</b> |
| <codeph>10000</codeph> (10 seconds)</p> |
| <p><b>Added in:</b> |
| <keyword keyref="impala34"/></p> |
| <p><b>Related information:</b> |
| <xref href="impala_max_result_spooling_mem.xml#MAX_RESULT_SPOOLING_MEM"/>, |
| <xref |
| href="impala_max_spilled_result_spooling_mem.xml#MAX_SPILLED_RESULT_SPOOLING_MEM" |
| />, <xref href="impala_spool_query_results.xml#SPOOL_QUERY_RESULTS"/></p> |
| </conbody> |
| </concept> |