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Change-Id: I07ec0a197de8a625788a3b0485d5ecf237e554ba Reviewed-on: http://gerrit.cloudera.org:8080/22576 Reviewed-by: Zoltan Borok-Nagy <boroknagyz@cloudera.com> Tested-by: Peter Rozsa <prozsa@cloudera.com>
86 lines
3.0 KiB
HTML
86 lines
3.0 KiB
HTML
<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
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<head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
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<meta name="copyright" content="(C) Copyright 2025" />
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<meta name="DC.rights.owner" content="(C) Copyright 2025" />
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<meta name="DC.Type" content="concept" />
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<meta name="DC.Title" content="LARGE_AGG_MEM_THRESHOLD Query Option (Impala 4.4 or higher only)" />
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<meta name="DC.Relation" scheme="URI" content="../topics/impala_set.html" />
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<meta name="prodname" content="Impala" />
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<meta name="version" content="Impala 3.4.x" />
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<meta name="DC.Format" content="XHTML" />
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<meta name="DC.Identifier" content="large_agg_mem_threshold" />
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<link rel="stylesheet" type="text/css" href="../commonltr.css" />
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<title>LARGE_AGG_MEM_THRESHOLD Query Option (Impala 4.4 or higher only)</title>
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</head>
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<body id="large_agg_mem_threshold">
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<h1 class="title topictitle1" id="ariaid-title1">LARGE_AGG_MEM_THRESHOLD Query Option (<span class="keyword">Impala 4.4</span> or higher only)</h1>
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<div class="body conbody">
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<p class="p">
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The threshold for the query planner to determine whether memory estimation for an
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aggregation node is large or not. Together with <code class="ph codeph">AGG_MEM_CORRELATION_FACTOR</code>,
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the planner will use this value to lower memory estimation for a large aggregation node.
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</p>
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<p class="p">
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Users can set this option value to 0.0 so the planner stays using the default
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NDV multiplication based-estimation. See <code class="ph codeph">AGG_MEM_CORRELATION_FACTOR</code>
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documentation for more detail.
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</p>
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<p class="p">
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<strong class="ph b">Type:</strong> integer
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</p>
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<p class="p">
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<strong class="ph b">Default:</strong>
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</p>
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<p class="p">
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<code class="ph codeph">536870912</code> (512 MB)
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</p>
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<p class="p">
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<strong class="ph b">Units:</strong> A numeric argument represents a size in bytes; you can also use a suffix
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of <code class="ph codeph">m</code> or <code class="ph codeph">mb</code> for megabytes, or <code class="ph codeph">g</code> or
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<code class="ph codeph">gb</code> for gigabytes. If you specify a value with unrecognized formats,
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subsequent queries fail with an error.
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</p>
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<p class="p">
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<strong class="ph b">Added in:</strong> <span class="keyword">Impala 4.4</span>
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</p>
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<p class="p">
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<strong class="ph b">Related information:</strong>
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</p>
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<p class="p">
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<a class="xref" href="impala_agg_mem_correlation_factor.html">AGG_MEM_CORRELATION_FACTOR Query Option (Impala 4.4 or higher only)</a>
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</p>
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</div>
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<div class="related-links">
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<div class="familylinks">
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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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</div>
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</div></body>
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</html> |