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| <meta name="DC.Title" content="SPOOL_QUERY_RESULTS Query Option" /> |
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| <body id="SPOOL_QUERY_RESULTS"> |
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| <h1 class="title topictitle1" id="ariaid-title1">SPOOL_QUERY_RESULTS Query Option</h1> |
| |
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| |
| <div class="body conbody"> |
| <p class="p">Use the <code class="ph codeph">SPOOL_QUERY_RESULTS</code> query option to enable query |
| result spooling, which is disabled by default.</p> |
| |
| <div class="p">Query result spooling controls how rows are returned to the client. <ul class="ul"> |
| <li class="li">When query result spooling is disabled (<code class="ph codeph">SPOOL_QUERY_RESULTS |
| = FALSE</code>), Impala relies on clients to fetch results to |
| trigger the generation of more result row batches until all the result |
| rows have been produced. If a client issues a query without fetching |
| all the results, the query fragments will continue to consume the |
| resources until the query is cancelled and unregistered, potentially |
| tying up resources and cause other queries to wait for extended period |
| of time in admission control.</li> |
| |
| <li class="li">When query result spooling is enabled (<code class="ph codeph">SPOOL_QUERY_RESULTS = |
| TRUE</code>), the result sets of queries are eagerly fetched and |
| spooled, either in memory or on disk. <p class="p">Once all result rows have |
| been fetched and stored in the spooling location, the resources are |
| freed up. Incoming client fetches can get the data from the spooled |
| results.</p> |
| </li> |
| |
| </ul> |
| </div> |
| |
| <p class="p"><strong class="ph b">Type:</strong> |
| <code class="ph codeph">BOOLEAN</code></p> |
| |
| <p class="p"><strong class="ph b">Default:</strong> |
| <code class="ph codeph">FALSE</code></p> |
| |
| <p class="p"><strong class="ph b">Added in:</strong> |
| <span class="keyword">Impala 3.4</span></p> |
| |
| <p class="p"><strong class="ph b">Related information:</strong> |
| <a class="xref" href="impala_default_spillable_buffer_size.html#default_spillable_buffer_size">DEFAULT_SPILLABLE_BUFFER_SIZE Query Option</a>, <a class="xref" href="impala_max_spilled_result_spooling_mem.html#MAX_SPILLED_RESULT_SPOOLING_MEM">MAX_SPILLED_RESULT_SPOOLING_MEM Query Option</a>, <a class="xref" href="impala_max_result_spooling_mem.html#MAX_RESULT_SPOOLING_MEM">MAX_RESULT_SPOOLING_MEM Query Option</a></p> |
| |
| </div> |
| |
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| <div class="parentlink"><strong>Parent topic:</strong> <a class="link" href="../topics/impala_set.html">SET Statement</a></div> |
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