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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>
93 lines
3.0 KiB
HTML
93 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="KUDU_READ_MODE Query Option (Impala 3.1 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="kudu_read_mode" />
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<link rel="stylesheet" type="text/css" href="../commonltr.css" />
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<title>KUDU_READ_MODE Query Option (Impala 3.1 or higher only)</title>
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</head>
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<body id="kudu_read_mode">
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<h1 class="title topictitle1" id="ariaid-title1">KUDU_READ_MODE Query Option (<span class="keyword">Impala 3.1</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 <code class="ph codeph">KUDU_READ_MODE</code> query option allows you to set a desired consistency
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level for scans of Kudu tables.
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</p>
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<p class="p">
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<strong class="ph b">Type:</strong> String
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</p>
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<p class="p">
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<strong class="ph b">Default:</strong> <code class="ph codeph">"DEFAULT"</code>
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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 3.1</span>
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</p>
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<p class="p">
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<strong class="ph b">Usage notes:</strong>
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</p>
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<div class="p">
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The following values are supported for the query option:
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<ul class="ul">
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<li class="li">
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<code class="ph codeph">"DEFAULT"</code>: The value of the startup flag,
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<code class="ph codeph">‑‑kudu_read_mode</code>, is used. </li>
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<li class="li">
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<code class="ph codeph">"READ_LATEST"</code>: Commonly known as the Read Committed isolation mode,
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in this mode, Kudu provides no consistency guarantees for this mode, except that all
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returned rows were committed at some point.
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</li>
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<li class="li">
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<code class="ph codeph">"READ_AT_SNAPSHOT"</code>: Kudu will take a snapshot of the current state of
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the data and perform the scan over the snapshot, possibly after briefly waiting for
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ongoing writes to complete. This provides "Read Your Writes" consistency within a
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single Impala session, except in the case of a Kudu leader change. See the Kudu
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documentation for more details.
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</li>
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</ul>
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</div>
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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> |