forked from laiweijian4/doc-exports
Lu, Huayi
a24ca60074
Reviewed-by: Hasko, Vladimir <vladimir.hasko@t-systems.com> Co-authored-by: Lu, Huayi <luhuayi@huawei.com> Co-committed-by: Lu, Huayi <luhuayi@huawei.com>
41 lines
7.9 KiB
HTML
41 lines
7.9 KiB
HTML
<a name="EN-US_TOPIC_0000001098655058"></a><a name="EN-US_TOPIC_0000001098655058"></a>
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<h1 class="topictitle1">Checkpoints</h1>
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<div id="body8662426"><div class="section" id="EN-US_TOPIC_0000001098655058__sd7daa0171e7245968cf6a44d968e1ad5"><a name="EN-US_TOPIC_0000001098655058__sd7daa0171e7245968cf6a44d968e1ad5"></a><a name="sd7daa0171e7245968cf6a44d968e1ad5"></a><h4 class="sectiontitle">checkpoint_segments</h4><p id="EN-US_TOPIC_0000001098655058__af3ffa17bd23a420e8eaf66f29998b87d"><strong id="EN-US_TOPIC_0000001098655058__a251c495f74a946a4909c813bc704b3e1">Parameter description</strong>: Specifies the minimum number of WAL segment files in the period specified by <a href="#EN-US_TOPIC_0000001098655058__s8acbdb7a59af4102bf229fcf4c889f37">checkpoint_timeout</a>. The size of each log file is 16 MB.</p>
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<p id="EN-US_TOPIC_0000001098655058__p4873133064319"><strong id="EN-US_TOPIC_0000001098655058__b162513720243">Type</strong>: SIGHUP</p>
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<p id="EN-US_TOPIC_0000001098655058__af6e4fb5b24d14955a064663ccc00bc45"><strong id="EN-US_TOPIC_0000001098655058__b29895242">Value range</strong>: an integer. The minimum value is <strong id="EN-US_TOPIC_0000001098655058__b47201151142917">1</strong>.</p>
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<p id="EN-US_TOPIC_0000001098655058__a28ba2b4d59dd444bb97cd0ad17f80017"><strong id="EN-US_TOPIC_0000001098655058__b5735075">Default value</strong>: <strong id="EN-US_TOPIC_0000001098655058__b842352706143016">64</strong></p>
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<div class="notice" id="EN-US_TOPIC_0000001098655058__note0657113584916"><span class="noticetitle"><img src="public_sys-resources/notice_3.0-en-us.png"> </span><div class="noticebody"><p id="EN-US_TOPIC_0000001098655058__p16571235194915">Increasing the value of this parameter speeds up the export of big data. Set this parameter based on <a href="#EN-US_TOPIC_0000001098655058__s8acbdb7a59af4102bf229fcf4c889f37">checkpoint_timeout</a> and <a href="dws_04_0893.html#EN-US_TOPIC_0000001145694783__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_0000001098655058__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_0000001098655058__s8acbdb7a59af4102bf229fcf4c889f37"><a name="EN-US_TOPIC_0000001098655058__s8acbdb7a59af4102bf229fcf4c889f37"></a><a name="s8acbdb7a59af4102bf229fcf4c889f37"></a><h4 class="sectiontitle">checkpoint_timeout</h4><p id="EN-US_TOPIC_0000001098655058__a155e64b1ce514021b3ef941ba94eb649"><strong id="EN-US_TOPIC_0000001098655058__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_0000001098655058__p1926513368473"><strong id="EN-US_TOPIC_0000001098655058__b46386196252">Type</strong>: SIGHUP</p>
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<p id="EN-US_TOPIC_0000001098655058__a31eddffceada4f3b8cc2e8cd0398b52f"><strong id="EN-US_TOPIC_0000001098655058__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_0000001098655058__a34223cb97ea141ce98b7f4ec8112e950"><strong id="EN-US_TOPIC_0000001098655058__en-us_topic_0058967679_b2933732">Default value</strong>: <strong id="EN-US_TOPIC_0000001098655058__b842352706154337">15min</strong></p>
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<div class="notice" id="EN-US_TOPIC_0000001098655058__note173837554499"><span class="noticetitle"><img src="public_sys-resources/notice_3.0-en-us.png"> </span><div class="noticebody"><p id="EN-US_TOPIC_0000001098655058__p13831155204915">If the value of <a href="#EN-US_TOPIC_0000001098655058__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_0000001145694783__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 class="section" id="EN-US_TOPIC_0000001098655058__sa9ae6e70ecf54d68a3f508b8fdac8375"><h4 class="sectiontitle">checkpoint_completion_target</h4><p id="EN-US_TOPIC_0000001098655058__a014ece4b71084c259f18a7de1819dce4"><strong id="EN-US_TOPIC_0000001098655058__en-us_topic_0059778936_a3bf66d7f92b9428aafc46873b348c21e">Parameter description</strong>: Specifies the target of checkpoint completion, as a fraction of total time between checkpoints.</p>
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<p id="EN-US_TOPIC_0000001098655058__p1267884734715"><strong id="EN-US_TOPIC_0000001098655058__b147964818254">Type</strong>: SIGHUP</p>
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<p id="EN-US_TOPIC_0000001098655058__a013230487f7445e5acc1d9a42352f413"><strong id="EN-US_TOPIC_0000001098655058__b1571122162719">Value range</strong>: 0.0 to 1.0. The default value 0.5 indicates that each checkpoint must be completed within 50% of the checkpoint interval.</p>
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<p id="EN-US_TOPIC_0000001098655058__a15ca92230c78417780bca454262bb163"><strong id="EN-US_TOPIC_0000001098655058__b1211034213116">Default value</strong>: <strong id="EN-US_TOPIC_0000001098655058__b311284220118">0.5</strong></p>
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</div>
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<div class="section" id="EN-US_TOPIC_0000001098655058__s34cf5c2d1fa9476ab90b105cada79e02"><h4 class="sectiontitle">checkpoint_warning</h4><p id="EN-US_TOPIC_0000001098655058__afc62de1413ec4e17bf96fa2360379e17"><strong id="EN-US_TOPIC_0000001098655058__b84235270620246">Parameter description</strong>: Specifies a time in seconds. If the checkpoint interval is close to this time due to filling of checkpoint segment files, a message is sent to the server log to increase the value of <a href="#EN-US_TOPIC_0000001098655058__sd7daa0171e7245968cf6a44d968e1ad5">checkpoint_segments</a>.</p>
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<p id="EN-US_TOPIC_0000001098655058__p38441156104716"><strong id="EN-US_TOPIC_0000001098655058__b188965462511">Type</strong>: SIGHUP</p>
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<p id="EN-US_TOPIC_0000001098655058__a0b64be17d4a44bce8fc280a07630c398"><strong id="EN-US_TOPIC_0000001098655058__b117515631415">Value range</strong>: an integer (unit: s). <strong id="EN-US_TOPIC_0000001098655058__b123841812154">0</strong> indicates that warning is disabled.</p>
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<p id="EN-US_TOPIC_0000001098655058__p1396231933818"><strong id="EN-US_TOPIC_0000001098655058__b84235270615047">Default value</strong>: <strong id="EN-US_TOPIC_0000001098655058__en-us_topic_0059778102_abcae9a6ad510442abf53c96ea5d201c5">5min</strong></p>
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<p id="EN-US_TOPIC_0000001098655058__a01861d33bc33496abe0456cfe95ed696"><strong id="EN-US_TOPIC_0000001098655058__a2a03498588d14cf5b735353345996338">Recommended value</strong>: <strong id="EN-US_TOPIC_0000001098655058__b84235270620437">5min</strong></p>
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</div>
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<div class="section" id="EN-US_TOPIC_0000001098655058__sedcc850aad9c4b3fac43a96a34adf7de"><h4 class="sectiontitle">checkpoint_wait_timeout</h4><p id="EN-US_TOPIC_0000001098655058__a197e55bf78f149178d6af7604d9fb0d9"><strong id="EN-US_TOPIC_0000001098655058__en-us_topic_0059778936_a96f576b1de1b47ab81c4ef95061f38f7">Parameter description</strong>: Specifies the longest time that the checkpoint waits for the checkpointer thread to start.</p>
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<p id="EN-US_TOPIC_0000001098655058__p418779174810"><strong id="EN-US_TOPIC_0000001098655058__b156191355112519">Type</strong>: SIGHUP</p>
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<p id="EN-US_TOPIC_0000001098655058__af1c6fbd79af642d7badfcc9693b98b9a"><strong id="EN-US_TOPIC_0000001098655058__en-us_topic_0059778936_a54e48c3257a74d049859538db2d3e624">Value range</strong>: an integer ranging from 2 to 3600 (s)</p>
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<p id="EN-US_TOPIC_0000001098655058__a3ded257e46f5441f932cbb63a0ebe184"><strong id="EN-US_TOPIC_0000001098655058__b842352706134828">Default value</strong>: <strong id="EN-US_TOPIC_0000001098655058__en-us_topic_0059778936_aca460a20d73849a7ae63c62104e066b2">1min</strong></p>
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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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