forked from docs/doc-exports
Lu, Huayi
ef0ada5a59
Reviewed-by: Pruthi, Vineet <vineet.pruthi@t-systems.com> Co-authored-by: Lu, Huayi <luhuayi@huawei.com> Co-committed-by: Lu, Huayi <luhuayi@huawei.com>
25 lines
4.2 KiB
HTML
25 lines
4.2 KiB
HTML
<a name="EN-US_TOPIC_0000001460882244"></a><a name="EN-US_TOPIC_0000001460882244"></a>
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<h1 class="topictitle1">Checkpoints</h1>
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<div id="body8662426"><div class="section" id="EN-US_TOPIC_0000001460882244__sd7daa0171e7245968cf6a44d968e1ad5"><a name="EN-US_TOPIC_0000001460882244__sd7daa0171e7245968cf6a44d968e1ad5"></a><a name="sd7daa0171e7245968cf6a44d968e1ad5"></a><h4 class="sectiontitle">checkpoint_segments</h4><p id="EN-US_TOPIC_0000001460882244__af3ffa17bd23a420e8eaf66f29998b87d"><strong id="EN-US_TOPIC_0000001460882244__b148061501713">Parameter description</strong>: minimum number of WAL segment files in the period specified by <a href="#EN-US_TOPIC_0000001460882244__s8acbdb7a59af4102bf229fcf4c889f37">checkpoint_timeout</a>. The size of each log file is 16 MB.</p>
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<p id="EN-US_TOPIC_0000001460882244__p4873133064319"><strong id="EN-US_TOPIC_0000001460882244__b162513720243">Type</strong>: SIGHUP</p>
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<p id="EN-US_TOPIC_0000001460882244__af6e4fb5b24d14955a064663ccc00bc45"><strong id="EN-US_TOPIC_0000001460882244__b29895242">Value range</strong>: an integer. The minimum value is <strong id="EN-US_TOPIC_0000001460882244__b47201151142917">1</strong>.</p>
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<p id="EN-US_TOPIC_0000001460882244__a28ba2b4d59dd444bb97cd0ad17f80017"><strong id="EN-US_TOPIC_0000001460882244__b2001761434101525">Default value</strong>: <strong id="EN-US_TOPIC_0000001460882244__b318163230101525">64</strong></p>
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<div class="notice" id="EN-US_TOPIC_0000001460882244__note0657113584916"><span class="noticetitle"><img src="public_sys-resources/notice_3.0-en-us.png"> </span><div class="noticebody"><p id="EN-US_TOPIC_0000001460882244__p16571235194915">Increasing the value of this parameter speeds up the export of big data. Set this parameter based on <a href="#EN-US_TOPIC_0000001460882244__s8acbdb7a59af4102bf229fcf4c889f37">checkpoint_timeout</a> and <a href="dws_04_0893.html#EN-US_TOPIC_0000001460563104__s9292cfbf38fa4b17b93e9a47330da753">shared_buffers</a>. This parameter affects the number of WAL log segment files that can be reused. Generally, the maximum number of reused files in the <strong id="EN-US_TOPIC_0000001460882244__b123561159366">pg_xlog</strong> folder is twice the number of checkpoint segments. The reused files are not deleted and are renamed to the WAL log segment files which will be later used.</p>
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</div></div>
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</div>
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<div class="section" id="EN-US_TOPIC_0000001460882244__s8acbdb7a59af4102bf229fcf4c889f37"><a name="EN-US_TOPIC_0000001460882244__s8acbdb7a59af4102bf229fcf4c889f37"></a><a name="s8acbdb7a59af4102bf229fcf4c889f37"></a><h4 class="sectiontitle">checkpoint_timeout</h4><p id="EN-US_TOPIC_0000001460882244__a155e64b1ce514021b3ef941ba94eb649"><strong id="EN-US_TOPIC_0000001460882244__en-us_topic_0059778936_a3ce1e9ea56d14d8ebce03022153b2749">Parameter description</strong>: Specifies the maximum time between automatic WAL checkpoints.</p>
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<p id="EN-US_TOPIC_0000001460882244__p1926513368473"><strong id="EN-US_TOPIC_0000001460882244__b46386196252">Type</strong>: SIGHUP</p>
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<p id="EN-US_TOPIC_0000001460882244__a31eddffceada4f3b8cc2e8cd0398b52f"><strong id="EN-US_TOPIC_0000001460882244__en-us_topic_0059778936_a017dc58f4ace4a378303f1819eebf032">Value range:</strong> an integer ranging from 30 to 3600 (s)</p>
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<p id="EN-US_TOPIC_0000001460882244__a34223cb97ea141ce98b7f4ec8112e950"><strong id="EN-US_TOPIC_0000001460882244__b1790586172101525">Default value</strong>: <strong id="EN-US_TOPIC_0000001460882244__b1171214063101525">15min</strong></p>
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<div class="notice" id="EN-US_TOPIC_0000001460882244__note173837554499"><span class="noticetitle"><img src="public_sys-resources/notice_3.0-en-us.png"> </span><div class="noticebody"><p id="EN-US_TOPIC_0000001460882244__p13831155204915">If the value of <a href="#EN-US_TOPIC_0000001460882244__sd7daa0171e7245968cf6a44d968e1ad5">checkpoint_segments</a> is increased, you need to increase the value of this parameter. The increase of them further requires the increase of <a href="dws_04_0893.html#EN-US_TOPIC_0000001460563104__s9292cfbf38fa4b17b93e9a47330da753">shared_buffers</a>. Consider all these parameters during setting.</p>
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</div></div>
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</div>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="dws_04_0900.html">Write Ahead Logs</a></div>
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</div>
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</div>
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