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doc-exports/docs/dws/dev/dws_04_0923.html
Lu, Huayi e6fa411af0 DWS DEV 830.201 version 
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>
2024-05-16 07:24:04 +00:00

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<a name="EN-US_TOPIC_0000001188482222"></a><a name="EN-US_TOPIC_0000001188482222"></a>
<h1 class="topictitle1">Automatic Cleanup</h1>
<div id="body8662426"><p id="EN-US_TOPIC_0000001188482222__en-us_topic_0059778244_p595074117714">The automatic cleanup process (<strong id="EN-US_TOPIC_0000001188482222__b10450913181017">autovacuum</strong>) in the system automatically runs the <strong id="EN-US_TOPIC_0000001188482222__b147932253834649">VACUUM</strong> and <strong id="EN-US_TOPIC_0000001188482222__b140381129034649">ANALYZE</strong> statements to reclaim the record space marked as deleted and update statistics about the table.</p>
<div class="section" id="EN-US_TOPIC_0000001188482222__s8d6c38309e594a16a07f79ae412b63c6"><a name="EN-US_TOPIC_0000001188482222__s8d6c38309e594a16a07f79ae412b63c6"></a><a name="s8d6c38309e594a16a07f79ae412b63c6"></a><h4 class="sectiontitle">autovacuum</h4><p id="EN-US_TOPIC_0000001188482222__ae4f6f9442dd546139c63415f9d833b32"><strong id="EN-US_TOPIC_0000001188482222__b11318514218">Parameter description</strong>: Specifies whether to start the automatic cleanup process (<strong id="EN-US_TOPIC_0000001188482222__b27983161113">autovacuum</strong>). Ensure that the <a href="dws_04_0920.html#EN-US_TOPIC_0000001233883261__s4682d08468f84845bfdc6ae9477126e8">track_counts</a> parameter is set to <strong id="EN-US_TOPIC_0000001188482222__en-us_topic_0085032001_en-us_topic_0058967612_b842352706111449">on</strong> before enabling the automatic cleanup process.</p>
<p id="EN-US_TOPIC_0000001188482222__p440031729"><strong id="EN-US_TOPIC_0000001188482222__b179783022418">Type</strong>: SIGHUP</p>
<p id="EN-US_TOPIC_0000001188482222__a871c10cb81fd4bee993a9cf00c5a91db"><strong id="EN-US_TOPIC_0000001188482222__en-us_topic_0059778244_en-us_topic_0058967612_b31827961">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001188482222__u9679d3fef2e1466aba7688aaff1fe697"><li id="EN-US_TOPIC_0000001188482222__lf92a3833049d4520827451527707b616"><strong id="EN-US_TOPIC_0000001188482222__b842352706143336">on</strong> indicates the database automatic cleanup process is enabled.</li><li id="EN-US_TOPIC_0000001188482222__li349315721115"><strong id="EN-US_TOPIC_0000001188482222__b51716176412">off</strong> indicates that the database automatic cleanup process is disabled.</li></ul>
<p id="EN-US_TOPIC_0000001188482222__p171314594114"><strong id="EN-US_TOPIC_0000001188482222__b2037433912415">Default value</strong>: <strong id="EN-US_TOPIC_0000001188482222__b15375133915414">on</strong></p>
<div class="note" id="EN-US_TOPIC_0000001188482222__note12291579265"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><div class="p" id="EN-US_TOPIC_0000001188482222__p722915715269">Set <strong id="EN-US_TOPIC_0000001188482222__b166753541520">autovacuum</strong> to <strong id="EN-US_TOPIC_0000001188482222__b842352706183654">on</strong> if you want to enable the function of automatically cleaning up two-phase transactions after the system recovers from faults.<ul id="EN-US_TOPIC_0000001188482222__ul6229657172614"><li id="EN-US_TOPIC_0000001188482222__l2ed94009fc62494583ad06aa6419edf6">If <strong id="EN-US_TOPIC_0000001188482222__b1497105501613">autovacuum</strong> is set to <strong id="EN-US_TOPIC_0000001188482222__b29781655101616">on</strong> and <a href="#EN-US_TOPIC_0000001188482222__s502d4304994d4da5bd3cda661aab27ac">autovacuum_max_workers</a> to <strong id="EN-US_TOPIC_0000001188482222__b49811557161">0</strong>, the <strong id="EN-US_TOPIC_0000001188482222__b522111112177">autovacuum</strong> process will not be automatically performed and only abnormal two-phase transactions are cleaned up after the system recovers from faults.</li><li id="EN-US_TOPIC_0000001188482222__li112291257112619">If <strong id="EN-US_TOPIC_0000001188482222__b155942540179">autovacuum</strong> is set to <strong id="EN-US_TOPIC_0000001188482222__b11596125431717">on</strong> and the value of <a href="#EN-US_TOPIC_0000001188482222__s502d4304994d4da5bd3cda661aab27ac">autovacuum_max_workers</a> is greater than <strong id="EN-US_TOPIC_0000001188482222__b18599135411171">0</strong>, the system will automatically clean up two-phase transactions and processes after recovering from faults.</li></ul>
</div>
</div></div>
<div class="notice" id="EN-US_TOPIC_0000001188482222__note6685958104114"><span class="noticetitle"><img src="public_sys-resources/notice_3.0-en-us.png"> </span><div class="noticebody"><div class="p" id="EN-US_TOPIC_0000001188482222__p117931248134311">Even if this parameter is set to <strong id="EN-US_TOPIC_0000001188482222__b05701956123212">off</strong>, the database initiates a cleanup process when transaction ID wraparound needs to be prevented. When a <strong id="EN-US_TOPIC_0000001188482222__b13195143241116">CREATE DATABASE</strong> or <strong id="EN-US_TOPIC_0000001188482222__b122021032201115">DROP DATABASE</strong> operation fails, the transaction may have been committed or rolled back on some nodes whereas some nodes are still in the prepared state. In this case, perform the following operations to manually restore the nodes:<ol id="EN-US_TOPIC_0000001188482222__ol1926717014298"><li id="EN-US_TOPIC_0000001188482222__li32677012292">Use the gs_clean tool (setting the <strong id="EN-US_TOPIC_0000001188482222__b4562358191415">option</strong> parameter to <strong id="EN-US_TOPIC_0000001188482222__b79652065150">-N</strong>) to query the xid of the abnormal two-phase transaction and nodes in the prepared status.</li><li id="EN-US_TOPIC_0000001188482222__li6267180192917">Log in to the nodes whose transactions are in the prepared status. Administrators connect to an available database such as <span id="EN-US_TOPIC_0000001188482222__text52672010291">gaussdb</span> to run the <strong id="EN-US_TOPIC_0000001188482222__b75607107148">SET xc_maintenance_mode = on</strong> statement.</li><li id="EN-US_TOPIC_0000001188482222__li132674022912">Commit or roll back the two-phase transaction based on the global transaction status.</li></ol>
</div>
</div></div>
</div>
<div class="section" id="EN-US_TOPIC_0000001188482222__section658130152017"><h4 class="sectiontitle">autovacuum_mode</h4><p id="EN-US_TOPIC_0000001188482222__p844791210525"><strong id="EN-US_TOPIC_0000001188482222__b057401215164">Parameter description</strong>: Specifies whether the <strong id="EN-US_TOPIC_0000001188482222__b13404103512212">autoanalyze</strong> or <strong id="EN-US_TOPIC_0000001188482222__b2751339122114">autovacuum</strong> function is enabled. This parameter is valid only when <strong id="EN-US_TOPIC_0000001188482222__b341225612161">autovacuum</strong> is set to <strong id="EN-US_TOPIC_0000001188482222__b207751457191614">on</strong>.</p>
<p id="EN-US_TOPIC_0000001188482222__p11716202593316"><strong id="EN-US_TOPIC_0000001188482222__b8366740112518">Type</strong>: SIGHUP</p>
<p id="EN-US_TOPIC_0000001188482222__p1488218235493"><strong id="EN-US_TOPIC_0000001188482222__b688412236498">Value range</strong>: enumerated values</p>
<ul id="EN-US_TOPIC_0000001188482222__ul1688422312497"><li id="EN-US_TOPIC_0000001188482222__li96231727051"><strong id="EN-US_TOPIC_0000001188482222__b1210712111174">analyze</strong> indicates that only <strong id="EN-US_TOPIC_0000001188482222__b173046381794">autoanalyze</strong> is performed.</li><li id="EN-US_TOPIC_0000001188482222__li155761262"><strong id="EN-US_TOPIC_0000001188482222__b1438311223170">vacuum</strong> indicates that only <strong id="EN-US_TOPIC_0000001188482222__b84171645298">autovacuum</strong> is performed.</li><li id="EN-US_TOPIC_0000001188482222__li39952131464"><strong id="EN-US_TOPIC_0000001188482222__b946503111179">mix</strong> indicates that both <strong id="EN-US_TOPIC_0000001188482222__b698355316916">autoanalyze</strong> and <strong id="EN-US_TOPIC_0000001188482222__b122145574917">autovacuum</strong> are performed.</li><li id="EN-US_TOPIC_0000001188482222__li1188442316495"><strong id="EN-US_TOPIC_0000001188482222__b14199939151712">none</strong> indicates that neither of them is performed.</li></ul>
<p id="EN-US_TOPIC_0000001188482222__p1887102354914"><strong id="EN-US_TOPIC_0000001188482222__b6524743191316">Default value</strong>: <strong id="EN-US_TOPIC_0000001188482222__b1481246131313">mix</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001188482222__section11642162416185"><h4 class="sectiontitle">autoanalyze_timeout</h4><p id="EN-US_TOPIC_0000001188482222__p1168744216181"><strong id="EN-US_TOPIC_0000001188482222__b15200164714174">Parameter description</strong>: Specifies the timeout period of <strong id="EN-US_TOPIC_0000001188482222__b157321647122220">autoanalyze</strong>. If the duration of <strong id="EN-US_TOPIC_0000001188482222__b1966775932216">analyze</strong> on a table exceeds the value of <strong id="EN-US_TOPIC_0000001188482222__b1888193218183">autoanalyze_timeout</strong>, <strong id="EN-US_TOPIC_0000001188482222__b1171413810239">analyze</strong> is automatically canceled.</p>
<p id="EN-US_TOPIC_0000001188482222__p4287171810334"><strong id="EN-US_TOPIC_0000001188482222__b1445784014255">Type</strong>: SIGHUP</p>
<p id="EN-US_TOPIC_0000001188482222__p1543044916184"><strong id="EN-US_TOPIC_0000001188482222__b3670177132412">Value range</strong>: an integer ranging from 0 to 2147483. The unit is second.</p>
<p id="EN-US_TOPIC_0000001188482222__p12459633151811"><strong id="EN-US_TOPIC_0000001188482222__b84235270615047">Default value</strong>: <strong id="EN-US_TOPIC_0000001188482222__en-us_topic_0059778102_abcae9a6ad510442abf53c96ea5d201c5">5min</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001188482222__section127431618386"><h4 class="sectiontitle">autovacuum_io_limits</h4><p id="EN-US_TOPIC_0000001188482222__p19802195019459"><strong id="EN-US_TOPIC_0000001188482222__b10864185520181">Parameter description</strong>: Specifies the upper limit of I/Os triggered by the <strong id="EN-US_TOPIC_0000001188482222__b548385010215">autovacuum</strong> process per second. This parameter has been discarded in version 8.1.2 and is reserved for compatibility with earlier versions. This parameter is invalid in the current version.</p>
<p id="EN-US_TOPIC_0000001188482222__p583341010330"><strong id="EN-US_TOPIC_0000001188482222__b170594016255">Type</strong>: SIGHUP</p>
<p id="EN-US_TOPIC_0000001188482222__p1980535010454"><strong id="EN-US_TOPIC_0000001188482222__en-us_topic_0059778244_en-us_topic_0058967612_b20082249">Value range</strong>: an integer ranging from –1 to 1073741823. <strong id="EN-US_TOPIC_0000001188482222__b11277185015373">–1</strong> indicates that the default Cgroup is used.</p>
<p id="EN-US_TOPIC_0000001188482222__p1380515503452"><strong id="EN-US_TOPIC_0000001188482222__b1556195535817">Default value</strong>: <strong id="EN-US_TOPIC_0000001188482222__b18557115513589">–1</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001188482222__s502d4304994d4da5bd3cda661aab27ac"><a name="EN-US_TOPIC_0000001188482222__s502d4304994d4da5bd3cda661aab27ac"></a><a name="s502d4304994d4da5bd3cda661aab27ac"></a><h4 class="sectiontitle">autovacuum_max_workers</h4><p id="EN-US_TOPIC_0000001188482222__a02743f17d05e49e89826be06b50d977a"><strong id="EN-US_TOPIC_0000001188482222__en-us_topic_0059778244_en-us_topic_0058967612_b39331917">Parameter description</strong>: Specifies the maximum number of automatic cleanup threads running at the same time.</p>
<p id="EN-US_TOPIC_0000001188482222__p1923610101295"><strong id="EN-US_TOPIC_0000001188482222__b6876152016616">Type</strong>: SIGHUP</p>
<p id="EN-US_TOPIC_0000001188482222__aed697a6422bb4d2b9772a1b00f6e618d"><strong id="EN-US_TOPIC_0000001188482222__en-us_topic_0059777487_en-us_topic_0058967566_b6696864">Value range</strong>: an integer ranging from 0 to 128. <strong id="EN-US_TOPIC_0000001188482222__b1727104773811">0</strong> indicates that <strong id="EN-US_TOPIC_0000001188482222__b1197312592212">autovacuum</strong> is disabled.</p>
<p id="EN-US_TOPIC_0000001188482222__a0055a0ef82e54f16ab80cf51d5d82146"><strong id="EN-US_TOPIC_0000001188482222__b842352706185015">Default value</strong>: <strong id="EN-US_TOPIC_0000001188482222__b842352706185018">3</strong></p>
<div class="note" id="EN-US_TOPIC_0000001188482222__note33239597113"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><ul id="EN-US_TOPIC_0000001188482222__ul81551253111210"><li id="EN-US_TOPIC_0000001188482222__li752795615415">This parameter works with <a href="#EN-US_TOPIC_0000001188482222__s8d6c38309e594a16a07f79ae412b63c6">autovacuum</a>. The rules for clearing system catalogs and user tables are as follows:<ul id="EN-US_TOPIC_0000001188482222__ul16546152104214"><li id="EN-US_TOPIC_0000001188482222__li1215645301214">When <strong id="EN-US_TOPIC_0000001188482222__b21428206681161">autovacuum_max_workers</strong> is set to <strong id="EN-US_TOPIC_0000001188482222__b2237594891161">0</strong>, <strong id="EN-US_TOPIC_0000001188482222__b15127998231161">autovacuum</strong> is disabled and no tables are cleared.</li><li id="EN-US_TOPIC_0000001188482222__li1615635314129">If <strong id="EN-US_TOPIC_0000001188482222__b7859867071161">autovacuum_max_workers &gt; 0</strong> and <strong id="EN-US_TOPIC_0000001188482222__b6853886531161">autovacuum = off</strong> are configured, the system only clears the system catalogs and column-store tables with delta tables enabled (such as <strong id="EN-US_TOPIC_0000001188482222__b13547033241161">vacuum delta tables</strong>, <strong id="EN-US_TOPIC_0000001188482222__b6707633731161">vacuum cudesc tables</strong>, and <strong id="EN-US_TOPIC_0000001188482222__b10801553091161">delta merge</strong>).</li><li id="EN-US_TOPIC_0000001188482222__li51564530125">If <strong id="EN-US_TOPIC_0000001188482222__b6057648721161">autovacuum_max_workers &gt; 0</strong> and <strong id="EN-US_TOPIC_0000001188482222__b489963111161">autovacuum = on</strong> are configured, all tables are cleared.</li></ul>
</li><li id="EN-US_TOPIC_0000001188482222__li8299824216">In 8.1.3, column-store primary tables are not cleared by default. You need to set the <strong id="EN-US_TOPIC_0000001188482222__b518365416355">colvacuum_threshold_scale_factor</strong> parameter to enable this function.</li></ul>
</div></div>
</div>
<div class="section" id="EN-US_TOPIC_0000001188482222__s41db964155f3432d8ebe76db75ea50cb"><h4 class="sectiontitle">autovacuum_naptime</h4><p id="EN-US_TOPIC_0000001188482222__abb4867d9d7764a5ba4ed9a2e0d1e6dc8"><strong id="EN-US_TOPIC_0000001188482222__en-us_topic_0059778244_en-us_topic_0058967612_b64864880">Parameter description</strong>: Specifies the interval between two automatic cleanup operations.</p>
<p id="EN-US_TOPIC_0000001188482222__p614254619319"><strong id="EN-US_TOPIC_0000001188482222__b1565212375267">Type</strong>: SIGHUP</p>
<p id="EN-US_TOPIC_0000001188482222__af4e85e3cf1144a2faaff468b11186d27"><strong id="EN-US_TOPIC_0000001188482222__b16644135514240">Value range</strong>: an integer ranging from 1 to 2147483. The unit is second.</p>
<p id="EN-US_TOPIC_0000001188482222__afe225e07d4f5493db2d230c4a1cf0562"><strong id="EN-US_TOPIC_0000001188482222__b842352706185119">Default value</strong>: <strong id="EN-US_TOPIC_0000001188482222__en-us_topic_0059778244_b15310055141954">60s</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001188482222__s2fba949c06b249f488e37ec0b3a1e8d7"><h4 class="sectiontitle"><strong id="EN-US_TOPIC_0000001188482222__b842352706185129">autovacuum_vacuum_threshold</strong></h4><p id="EN-US_TOPIC_0000001188482222__a0fdbaa013cb048c1b66f771999a6845d"><strong id="EN-US_TOPIC_0000001188482222__b27595912_2">Parameter description</strong>: Specifies the threshold for triggering the <strong id="EN-US_TOPIC_0000001188482222__b142400396734649">VACUUM</strong> operation. When the number of deleted or updated records in a table exceeds the specified threshold, the <strong id="EN-US_TOPIC_0000001188482222__b155649792034649">VACUUM</strong> operation is executed on this table.</p>
<p id="EN-US_TOPIC_0000001188482222__p3700403312"><strong id="EN-US_TOPIC_0000001188482222__b131721538152615">Type</strong>: SIGHUP</p>
<p id="EN-US_TOPIC_0000001188482222__a4b35622c9c554230be3c7ec90fbf6451"><strong id="EN-US_TOPIC_0000001188482222__b113836715259">Value range</strong>: an integer ranging from <strong id="EN-US_TOPIC_0000001188482222__b97231818183413">0</strong> to <strong id="EN-US_TOPIC_0000001188482222__b3263122173415">INT_MAX</strong></p>
<p id="EN-US_TOPIC_0000001188482222__a074ca27bd9e14c92afc20b727d2a43d7"><strong id="EN-US_TOPIC_0000001188482222__en-us_topic_0058967612_b1551330">Default value</strong>: <strong id="EN-US_TOPIC_0000001188482222__b84235270616249">50</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001188482222__s221c28f820064e7890b242b5ad95c1bd"><h4 class="sectiontitle">autovacuum_analyze_threshold</h4><p id="EN-US_TOPIC_0000001188482222__a6a11767b3e854947bd41d6b08a1077dc"><strong id="EN-US_TOPIC_0000001188482222__b27595912_4">Parameter description</strong>: Specifies the threshold for triggering the <strong id="EN-US_TOPIC_0000001188482222__b46878498534649">ANALYZE</strong> operation. When the number of deleted, inserted, or updated records in a table exceeds the specified threshold, the <strong id="EN-US_TOPIC_0000001188482222__b99369388834649">ANALYZE</strong> operation is executed on this table.</p>
<p id="EN-US_TOPIC_0000001188482222__p370623203119"><strong id="EN-US_TOPIC_0000001188482222__b16423123812263">Type</strong>: SIGHUP</p>
<p id="EN-US_TOPIC_0000001188482222__a77cf4fbf33ef488b831c180e2351fec5"><strong id="EN-US_TOPIC_0000001188482222__b937374499">Value range</strong>: an integer ranging from <strong id="EN-US_TOPIC_0000001188482222__b195771730123420">0</strong> to <strong id="EN-US_TOPIC_0000001188482222__b9254173373415">INT_MAX</strong></p>
<p id="EN-US_TOPIC_0000001188482222__a0b513579dd254e11be781fb3d7b87540"><strong id="EN-US_TOPIC_0000001188482222__b361272842">Default value</strong>:</p>
<ul id="EN-US_TOPIC_0000001188482222__ul159063464418"><li id="EN-US_TOPIC_0000001188482222__li164061033184410">If the current cluster is upgraded from an earlier version to 8.1.3, the default value is <strong id="EN-US_TOPIC_0000001188482222__b204561608491">10000</strong> to ensure forward compatibility.</li><li id="EN-US_TOPIC_0000001188482222__li99071041448">If the current cluster version is 8.1.3, the default value is <strong id="EN-US_TOPIC_0000001188482222__b4374112114919">50</strong>.</li></ul>
</div>
<div class="section" id="EN-US_TOPIC_0000001188482222__sd4638f5991b8491d90d552345ee6c5ec"><h4 class="sectiontitle">autovacuum_vacuum_scale_factor</h4><p id="EN-US_TOPIC_0000001188482222__a5cd30f2e9f764a848306cbbba4f09b45"><strong id="EN-US_TOPIC_0000001188482222__b21399388_1">Parameter description</strong>: Specifies the size scaling factor of a table added to the <strong id="EN-US_TOPIC_0000001188482222__b188598810734649">autovacuum_vacuum_threshold</strong> parameter when a <strong id="EN-US_TOPIC_0000001188482222__b142441122634649">VACUUM</strong> event is triggered.</p>
<p id="EN-US_TOPIC_0000001188482222__p810818259313"><strong id="EN-US_TOPIC_0000001188482222__b126331138182613">Type</strong>: SIGHUP</p>
<p id="EN-US_TOPIC_0000001188482222__a52a6cfcfadf348749a639ff428689f9f"><strong id="EN-US_TOPIC_0000001188482222__en-us_topic_0059778244_en-us_topic_0058967612_b23973035">Value range</strong>: a floating point number ranging from 0.0 to 100.0</p>
<p id="EN-US_TOPIC_0000001188482222__adb5e021dd35948b291c230121f148318"><strong id="EN-US_TOPIC_0000001188482222__b60786481_1">Default value</strong>: <strong id="EN-US_TOPIC_0000001188482222__b84235270610657">0.2</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001188482222__s52c6ca5c984e4ac78ec99d2cc2bbda68"><h4 class="sectiontitle">autovacuum_analyze_scale_factor</h4><p id="EN-US_TOPIC_0000001188482222__a42d3b7a643944b4791e1715b16c1d0e0"><strong id="EN-US_TOPIC_0000001188482222__b21399388_4">Parameter description</strong>: Specifies the size scaling factor of a table added to the <strong id="EN-US_TOPIC_0000001188482222__b11831116634649">autovacuum_analyze_threshold</strong> parameter when an <strong id="EN-US_TOPIC_0000001188482222__b160157370634649">ANALYZE</strong> event is triggered.</p>
<p id="EN-US_TOPIC_0000001188482222__p201751017103117"><strong id="EN-US_TOPIC_0000001188482222__b14808738102618">Type</strong>: SIGHUP</p>
<p id="EN-US_TOPIC_0000001188482222__a98b82bee8c454e0aa86dbd235bad6f2c"><strong id="EN-US_TOPIC_0000001188482222__en-us_topic_0059778244_en-us_topic_0058967612_b28275581">Value range</strong>: a floating point number ranging from 0.0 to 100.0</p>
<p id="EN-US_TOPIC_0000001188482222__a4b41014dcf414bc8b95ca428de9ce186"><strong id="EN-US_TOPIC_0000001188482222__b60786481_3">Default value</strong>:</p>
<ul id="EN-US_TOPIC_0000001188482222__ul2031601775015"><li id="EN-US_TOPIC_0000001188482222__li33161217175011">If the current cluster is upgraded from an earlier version to 8.1.3, the default value is <strong id="EN-US_TOPIC_0000001188482222__b3257121635011">0.25</strong> to ensure forward compatibility.</li><li id="EN-US_TOPIC_0000001188482222__li13316117185013">If the current cluster version is 8.1.3, the default value is <strong id="EN-US_TOPIC_0000001188482222__b7920152520509">0.1</strong>.</li></ul>
</div>
<div class="section" id="EN-US_TOPIC_0000001188482222__s60e0fbc2967c44b3bb6c53c29e9c772e"><h4 class="sectiontitle">autovacuum_freeze_max_age</h4><p id="EN-US_TOPIC_0000001188482222__a378c10d2879740ebbc4d0af3d2b16a06"><strong id="EN-US_TOPIC_0000001188482222__b47690497">Parameter description</strong>: Specifies the maximum age (in transactions) that a table's <strong id="EN-US_TOPIC_0000001188482222__b2581408191">pg_class.relfrozenxid</strong> column can attain before a VACUUM operation is forced to prevent transaction ID wraparound within the table. </p>
<p id="EN-US_TOPIC_0000001188482222__p4799185915408">The old files under the subdirectory of <strong id="EN-US_TOPIC_0000001188482222__b02179223265">pg_clog/</strong> can also be deleted by the VACUUM operation. Even if the automatic cleanup process is forbidden, the system will invoke the automatic cleanup process to prevent the cyclic repetition.</p>
<p id="EN-US_TOPIC_0000001188482222__p173051033183017"><strong id="EN-US_TOPIC_0000001188482222__b1198163872615">Type</strong>: SIGHUP</p>
<p id="EN-US_TOPIC_0000001188482222__a8f62dcc043de4c81ba2ee70b16555c70"><strong id="EN-US_TOPIC_0000001188482222__b192225161317">Value range</strong>: an integer ranging from 100000 to 576460752303423487</p>
<p id="EN-US_TOPIC_0000001188482222__a99092a1b31824e1ca4fd671644763d90"><strong id="EN-US_TOPIC_0000001188482222__b1887492023910">Default value</strong>: <strong id="EN-US_TOPIC_0000001188482222__b1687582083913">4000000000</strong></p>
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<div class="section" id="EN-US_TOPIC_0000001188482222__sd3082605f4ef4a4383807a078c38bc1e"><h4 class="sectiontitle">autovacuum_vacuum_cost_delay</h4><p id="EN-US_TOPIC_0000001188482222__aa9e29e9224b243758df82ae2606aab5e"><strong id="EN-US_TOPIC_0000001188482222__en-us_topic_0059778244_en-us_topic_0058967612_b39055335">Parameter description</strong>: Specifies the value of the cost delay used in the <strong id="EN-US_TOPIC_0000001188482222__b95544175227">autovacuum</strong> operation.</p>
<p id="EN-US_TOPIC_0000001188482222__p62421778312"><strong id="EN-US_TOPIC_0000001188482222__b71411939152618">Type</strong>: SIGHUP</p>
<p id="EN-US_TOPIC_0000001188482222__ac28c2d20ef894e2e9c8517e5a942abce"><strong id="EN-US_TOPIC_0000001188482222__en-us_topic_0059778244_en-us_topic_0058967612_b21083041">Value range</strong>: an integer ranging from –1 to 100. The unit is ms. <strong id="EN-US_TOPIC_0000001188482222__b185331434133917">-1</strong> indicates that the normal vacuum cost delay is used.</p>
<p id="EN-US_TOPIC_0000001188482222__af37beecf08954cfcaa966bedcf008dbd"><strong id="EN-US_TOPIC_0000001188482222__b189481635144016">Default value</strong>: <strong id="EN-US_TOPIC_0000001188482222__b895053544011">2ms</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001188482222__s0813cb847c624c68af2c910e1cb1b7f9"><h4 class="sectiontitle">autovacuum_vacuum_cost_limit</h4><p id="EN-US_TOPIC_0000001188482222__abd05f61046554cbba319c60e10b0eaef"><strong id="EN-US_TOPIC_0000001188482222__b39055335_4">Parameter description</strong>: Specifies the value of the cost limit used in the <strong id="EN-US_TOPIC_0000001188482222__b45221626102213">autovacuum</strong> operation.</p>
<p id="EN-US_TOPIC_0000001188482222__p1134113462309"><strong id="EN-US_TOPIC_0000001188482222__b2310143920261">Type</strong>: SIGHUP</p>
<p id="EN-US_TOPIC_0000001188482222__aa85295cf591b496fba57f09ab1475ac1"><strong id="EN-US_TOPIC_0000001188482222__b1656376339">Value range</strong>: an integer ranging from –1 to 10000. <strong id="EN-US_TOPIC_0000001188482222__b6332122119415">-1</strong> indicates that the normal vacuum cost limit is used.</p>
<p id="EN-US_TOPIC_0000001188482222__a6cf0563044774291ad5ac769f3853455"><strong id="EN-US_TOPIC_0000001188482222__b53628433514291">Default value</strong>: <strong id="EN-US_TOPIC_0000001188482222__b164450946414291">–1</strong></p>
</div>
</div>
<div>
<div class="familylinks">
<div class="parentlink"><strong>Parent topic:</strong> <a href="dws_04_0883.html">GUC Parameters</a></div>
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