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doc-exports/docs/dws/dev/dws_04_0936.html
luhuayi 177cd61a57 DWS DEVG 910.211 version 
Reviewed-by: Pruthi, Vineet <vineet.pruthi@t-systems.com>
Co-authored-by: luhuayi <luhuayi@huawei.com>
Co-committed-by: luhuayi <luhuayi@huawei.com>
2025-05-05 07:44:03 +00:00

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<a name="EN-US_TOPIC_0000001764491796"></a><a name="EN-US_TOPIC_0000001764491796"></a>
<h1 class="topictitle1">Developer Operations</h1>
<div id="body8662426"><div class="section" id="EN-US_TOPIC_0000001764491796__section5236926112310"><h4 class="sectiontitle">enable_light_colupdate</h4><p id="EN-US_TOPIC_0000001764491796__p72361726112312"><strong id="EN-US_TOPIC_0000001764491796__b2011513209113">Parameter description</strong>: Specifies whether to enable the lightweight column-store update.</p>
<p id="EN-US_TOPIC_0000001764491796__p9236226202310"><strong id="EN-US_TOPIC_0000001764491796__b44741056229">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p13236526132313"><strong id="EN-US_TOPIC_0000001764491796__b540139201819">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__ul823752613230"><li id="EN-US_TOPIC_0000001764491796__li4237122612319"><strong id="EN-US_TOPIC_0000001764491796__b998217114227">on</strong> indicates that the lightweight column-store update is enabled.</li><li id="EN-US_TOPIC_0000001764491796__li11237112619234"><strong id="EN-US_TOPIC_0000001764491796__b24381234112211">off</strong> indicates that the lightweight column-store update is disabled.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__p123772632314"><strong id="EN-US_TOPIC_0000001764491796__b10699182711187">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b18699152716186">off</strong></p>
<div class="note" id="EN-US_TOPIC_0000001764491796__note1328482481213"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><p id="EN-US_TOPIC_0000001764491796__p142841524161211">There is a low probability that an error is reported when lightweight <strong id="EN-US_TOPIC_0000001764491796__b72348203256">UPDATE</strong> and backend column-store <strong id="EN-US_TOPIC_0000001764491796__b250811301251">AUTOVACUUM</strong> coexist. You can run <strong id="EN-US_TOPIC_0000001764491796__b132301923266">ALTER TABLE</strong> to set the table-level parameter <strong id="EN-US_TOPIC_0000001764491796__b99929186261">enable_column_autovacuum_garbage</strong> to <strong id="EN-US_TOPIC_0000001764491796__b855015233265">off</strong> to avoid this issue. If the table-level parameter <strong id="EN-US_TOPIC_0000001764491796__b211577112115">enable_column_autovacuum_garbage</strong> is set to <strong id="EN-US_TOPIC_0000001764491796__b4648199112111">off</strong>, the backend column-store <strong id="EN-US_TOPIC_0000001764491796__b15316145052613">AUTOVACUUM</strong> of the table is disabled.</p>
</div></div>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__s9b7f64f4f112450490c8c74b520cc915"><a name="EN-US_TOPIC_0000001764491796__s9b7f64f4f112450490c8c74b520cc915"></a><a name="s9b7f64f4f112450490c8c74b520cc915"></a><h4 class="sectiontitle">enable_fast_query_shipping</h4><p id="EN-US_TOPIC_0000001764491796__a68176f11af7249f48e67ee4b0782b562"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b842352706161736">Parameter description</strong>: Specifies whether to use the distributed framework for a query planner.</p>
<p id="EN-US_TOPIC_0000001764491796__p8226203042311"><strong id="EN-US_TOPIC_0000001764491796__b937211317480">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__a757ac543827e4e4f916b701105eaa75b"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b10741640_1">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__u10b2a101bc86425dbe47de0ca89c878d"><li id="EN-US_TOPIC_0000001764491796__ld03c6b8c6f2c456c99ce7f03ea3304fb"><strong id="EN-US_TOPIC_0000001764491796__b842352706171310">on</strong> indicates that execution plans are generated on CNs and DNs separately.</li><li id="EN-US_TOPIC_0000001764491796__l4754a99b0b5c4d0cbd9f8269fa585358"><strong id="EN-US_TOPIC_0000001764491796__b944056124171319">off</strong> indicates that the distributed framework is used. Execution plans are generated on CNs and then sent to DNs for execution.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__a5949a8effdbd4cbe9d7cdd3dbe25245b"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_aa151e2b3bcc44a9fbb6d168392bfb2a8">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b842352706143455">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section38449529239"><h4 class="sectiontitle">enable_trigger_shipping</h4><p id="EN-US_TOPIC_0000001764491796__p1684445212236"><strong id="EN-US_TOPIC_0000001764491796__b9556145816383">Parameter description</strong>: Specifies whether the trigger can be pushed to DNs for execution.</p>
<p id="EN-US_TOPIC_0000001764491796__p822820541374"><strong id="EN-US_TOPIC_0000001764491796__b215711159489">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p88451652172317"><strong id="EN-US_TOPIC_0000001764491796__b108364720">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__ul11845125212232"><li id="EN-US_TOPIC_0000001764491796__li58451252172319"><strong id="EN-US_TOPIC_0000001764491796__b2769212153911">on</strong> indicates that the trigger can be pushed to DNs for execution.</li><li id="EN-US_TOPIC_0000001764491796__li7845105219233"><strong id="EN-US_TOPIC_0000001764491796__b46855479396">off</strong> indicates that the trigger cannot be pushed to DNs. It must be executed on the CN.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__p208453520235"><strong id="EN-US_TOPIC_0000001764491796__b1631435816">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b1324929288">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__s8bc5a77e871d44c58a8794aa67e22bda"><h4 class="sectiontitle">enable_remotejoin</h4><p id="EN-US_TOPIC_0000001764491796__ab6d6c76b6ee6465c82d16f405f1af815"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_a69d70227e2d945a1b5c9a7f42d244fb6">Parameter description:</strong> Specifies whether JOIN operation plans can be delivered to DNs for execution.</p>
<p id="EN-US_TOPIC_0000001764491796__p1994615119382"><strong id="EN-US_TOPIC_0000001764491796__b9744121519483">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__a3ebd295205e542cca3529fa2009c23d2"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b10741640_3">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__u868c5d7f3bb0475199da69d0fd617fe3"><li id="EN-US_TOPIC_0000001764491796__l08acbf11397a4616a8dce71066a31b58"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b84235270617174_1">on</strong> indicates that JOIN operation plans can be delivered to DNs for execution.</li><li id="EN-US_TOPIC_0000001764491796__l8ae82932916b49c287a321626b18ed41"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b1349329973171712_1">off</strong> indicates that JOIN operation plans cannot be delivered to DNs for execution.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__a371dc7f4a8bb414b9dc61a0007f6927a"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_ae6880ce5466c4e13bdd758212edfcfa1">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b842352706143542">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__sb2240017245f4f19bc88b277086efca5"><h4 class="sectiontitle">enable_remotegroup</h4><p id="EN-US_TOPIC_0000001764491796__ae15190f7d24145d383647184ea04dc7f"><strong id="EN-US_TOPIC_0000001764491796__b1169914253414">Parameter description:</strong> Specifies whether the execution plans of <strong id="EN-US_TOPIC_0000001764491796__b1870017258413">GROUP BY</strong> and <strong id="EN-US_TOPIC_0000001764491796__b170152510414">AGGREGATE</strong> can be delivered to DNs for execution.</p>
<p id="EN-US_TOPIC_0000001764491796__p9469112382"><strong id="EN-US_TOPIC_0000001764491796__b19145101654813">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__a1de1f6d82a914d988acd4d735e656b8c"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b10741640_5">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__u3776878a482e48faa55cafbdf0a113de"><li id="EN-US_TOPIC_0000001764491796__lfea5ba4096f84759a0c4b0ba6a4f4ac4"><strong id="EN-US_TOPIC_0000001764491796__b157517084214">on</strong> indicates that the execution plans of <strong id="EN-US_TOPIC_0000001764491796__b1756015423">GROUP BY</strong> and <strong id="EN-US_TOPIC_0000001764491796__b157615018429">AGGREGATE</strong> can be delivered to DNs for execution.</li><li id="EN-US_TOPIC_0000001764491796__l84eaea0b3e524552b089104f7b49a700"><strong id="EN-US_TOPIC_0000001764491796__b164851014164110">off</strong> indicates that the execution plans of <strong id="EN-US_TOPIC_0000001764491796__b12485131417412">GROUP BY</strong> and <strong id="EN-US_TOPIC_0000001764491796__b94862146410">AGGREGATE</strong> cannot be delivered to DNs for execution.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__aa10eb6b9c8e34382898a85f464fcf103"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_a724a1d7e94ce4608b5f61929de038644">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b842352706143724">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__s11c7f4a137e7460fbcbd2a4d2fcd9204"><h4 class="sectiontitle">enable_remotelimit</h4><p id="EN-US_TOPIC_0000001764491796__ab3440e31dab44ff4bacfe03bef1cf0c4"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b179411486172024">Parameter description</strong>: Specifies whether the execution plan specified in the LIMIT clause can be pushed down to DNs for execution.</p>
<p id="EN-US_TOPIC_0000001764491796__p16604102073811"><strong id="EN-US_TOPIC_0000001764491796__b042581616484">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__acf840ad284b24d3c9ad65055b7ea857e"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b10741640_7">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__ub0b637f122654199b6703d8217ee9212"><li id="EN-US_TOPIC_0000001764491796__l41b180c143e8480480ead58176df9c5a"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b84235270617174_5">on</strong> indicates that the execution plan specified in the LIMIT clause can be pushed down to DNs for execution.</li><li id="EN-US_TOPIC_0000001764491796__la84c159608864ba39c88f819ea43ed03"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b1349329973171712_5">off</strong> indicates that the execution plan specified in the LIMIT clause cannot be delivered to DNs for execution.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__aeaba26fb6e464dc4958691b4faf2381d"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_abad37691a20b432582ae726a5566ec02">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b842352706143839">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section93326214434"><h4 class="sectiontitle">enable_limit_stop</h4><p id="EN-US_TOPIC_0000001764491796__p119861139443"><strong id="EN-US_TOPIC_0000001764491796__b1940754711123">Parameter description</strong>: whether to enable the <strong id="EN-US_TOPIC_0000001764491796__b1305617734103924">early stop</strong> optimization for <strong id="EN-US_TOPIC_0000001764491796__b483642900103924">LIMIT</strong> statements. For a <strong id="EN-US_TOPIC_0000001764491796__b360093310103924">LIMIT n</strong> statement, if <strong id="EN-US_TOPIC_0000001764491796__b1309133848103924">early stop</strong> is enabled, the CN requests the DN to end the execution after receiving n pieces of data. This method is applicable to complex queries with <strong id="EN-US_TOPIC_0000001764491796__b105624828103924">LIMIT</strong>. This parameter is supported only by clusters of version 8.1.3.320 or later.</p>
<p id="EN-US_TOPIC_0000001764491796__p8583514447"><strong id="EN-US_TOPIC_0000001764491796__b1874029599">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p9593515448"><strong id="EN-US_TOPIC_0000001764491796__b1155529225">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__ul195925184419"><li id="EN-US_TOPIC_0000001764491796__li19510123711440"><strong id="EN-US_TOPIC_0000001764491796__b187681943105610">on</strong> indicates that <strong id="EN-US_TOPIC_0000001764491796__b17769194310563">early stop</strong> is enabled for LIMIT statements.</li><li id="EN-US_TOPIC_0000001764491796__li115915564414"><strong id="EN-US_TOPIC_0000001764491796__b1231860706103924">off</strong> indicates that <strong id="EN-US_TOPIC_0000001764491796__b1408518054103924">early stop</strong> is disabled for LIMIT statements.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__p7590514446"><strong id="EN-US_TOPIC_0000001764491796__b594954157">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b1931409859">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__sad98e37675e1431e8f386cfd7b43c0c0"><h4 class="sectiontitle">enable_remotesort</h4><p id="EN-US_TOPIC_0000001764491796__aa62ac95fa0244da49b9f9f1030845882"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_ac8f894e1d6f94603b957daeb694887ce">Parameter description:</strong> Specifies whether the execution plan of the ORDER BY clause can be delivered to DNs for execution.</p>
<p id="EN-US_TOPIC_0000001764491796__p67529113811"><strong id="EN-US_TOPIC_0000001764491796__b666351610480">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__a205bc519657b459b8002a71ba2668828"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b10741640_9">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__u8198ccf46a5b4c03b4d4057f780b5332"><li id="EN-US_TOPIC_0000001764491796__ld89eda7937eb41d181bea4d0d22053a8"><strong id="EN-US_TOPIC_0000001764491796__b84235270617174">on</strong> indicates that the execution plan of the ORDER BY clause can be delivered to DNs for execution.</li><li id="EN-US_TOPIC_0000001764491796__l328eb35b743d4c0e81332da92d9f5c3f"><strong id="EN-US_TOPIC_0000001764491796__b1349329973171712">off</strong> indicates that the execution plan of the ORDER BY clause cannot be delivered to DNs for execution.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__ad1c67ef19d4a48cc8f9829daa9615839"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_a54aa90819f334704a86ce6893b38d77e">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b842352706143920">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section112190396354"><h4 class="sectiontitle">enable_join_pseudoconst</h4><p id="EN-US_TOPIC_0000001764491796__p82195398354"><strong id="EN-US_TOPIC_0000001764491796__b10240648209">Parameter description</strong>: Specifies whether joining with the pseudo constant is allowed. A pseudo constant indicates that the variables on both sides of a join are identical to the same constant.</p>
<p id="EN-US_TOPIC_0000001764491796__p399519366385"><strong id="EN-US_TOPIC_0000001764491796__b108551316104810">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p15219173913352"><strong id="EN-US_TOPIC_0000001764491796__b14865122200">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__ul1421903919354"><li id="EN-US_TOPIC_0000001764491796__li521983914353"><strong id="EN-US_TOPIC_0000001764491796__b545171910116">on</strong> indicates that joining with the pseudo constant is allowed.</li><li id="EN-US_TOPIC_0000001764491796__li14219133911355"><strong id="EN-US_TOPIC_0000001764491796__b21041326418">off</strong> indicates that joining with the pseudo constant is not allowed.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__p02193391354"><strong id="EN-US_TOPIC_0000001764491796__b208874292112">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b16887192914114">off</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section74494615103"><h4 class="sectiontitle">cost_model_version</h4><p id="EN-US_TOPIC_0000001764491796__p544184617101"><strong id="EN-US_TOPIC_0000001764491796__b10419125416712">Parameter description</strong>: Specifies the model used for cost estimation in the application scenario. This parameter affects the distinct estimation of the expression, HashJoin cost model, estimation of the number of rows, distribution key selection during redistribution, and estimation of the number of aggregate rows.</p>
<p id="EN-US_TOPIC_0000001764491796__p174484641010"><strong id="EN-US_TOPIC_0000001764491796__b1892375041916">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p54411462108"><strong id="EN-US_TOPIC_0000001764491796__b5681551507">Value range</strong>: <strong id="EN-US_TOPIC_0000001764491796__b17682125101">0</strong>, <strong id="EN-US_TOPIC_0000001764491796__b46821451701">1</strong>, <strong id="EN-US_TOPIC_0000001764491796__b4683251002">2</strong>, <strong id="EN-US_TOPIC_0000001764491796__b18683165800">3</strong>, or <strong id="EN-US_TOPIC_0000001764491796__b176831251202">4</strong></p>
<ul id="EN-US_TOPIC_0000001764491796__ul15785113214221"><li id="EN-US_TOPIC_0000001764491796__li37861432122218"><strong id="EN-US_TOPIC_0000001764491796__b152501221172320">0</strong> indicates that the original cost estimation model is used.</li><li id="EN-US_TOPIC_0000001764491796__li2078673282219"><strong id="EN-US_TOPIC_0000001764491796__b17212123122410">1</strong> indicates that the enhanced distinct estimation of the expression, HashJoin cost estimation model, estimation of the number of rows, distribution key selection during redistribution, and estimation of the number of aggregate rows are used on the basis of <strong id="EN-US_TOPIC_0000001764491796__b1594444318283">0</strong>.</li><li id="EN-US_TOPIC_0000001764491796__li1691422145214"><strong id="EN-US_TOPIC_0000001764491796__b752515062818">2</strong> indicates that the ANALYZE sampling algorithm with better randomicity is used on the basis of <strong id="EN-US_TOPIC_0000001764491796__b11194185993116">1</strong> to improve the accuracy of statistics collection.</li><li id="EN-US_TOPIC_0000001764491796__li1916662016459"><strong id="EN-US_TOPIC_0000001764491796__b18782135719469">3</strong> indicates that the broadcast cost estimation in large cluster scenarios is optimized based on <strong id="EN-US_TOPIC_0000001764491796__b15921550154911">2</strong> so that the optimizer can select a better plan. This option is supported only by clusters of version 8.3.0 or later.</li><li id="EN-US_TOPIC_0000001764491796__li174411455102613"><strong id="EN-US_TOPIC_0000001764491796__b164719714110">4</strong> indicates that in addition to the optimizations made to the cost estimation of hashjoin parallelization, skew, and column-store index ordering in <strong id="EN-US_TOPIC_0000001764491796__b115351819110">3</strong>, there are also optimized row estimations for coalesce expressions and improved recognition of skew optimization for subquery constant output columns during joins.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__p444246151011"><strong id="EN-US_TOPIC_0000001764491796__b164231959240">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b84234532419">4</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__s32fe2a2b19b1450baedd6e65d4bac6ea"><h4 class="sectiontitle">debug_assertions</h4><p id="EN-US_TOPIC_0000001764491796__a05cfea29c6214a519773694009e5707a"><strong id="EN-US_TOPIC_0000001764491796__b50318994434350">Parameter description</strong>: Specifies whether to enable various assertion checks. This parameter assists in debugging. If you are experiencing strange problems or crashes, set this parameter to <strong id="EN-US_TOPIC_0000001764491796__b595816234528">on</strong> to identify programming defects. To use this parameter, the macro USE_ASSERT_CHECKING must be defined (through the configure option <strong id="EN-US_TOPIC_0000001764491796__b14619182605218">--enable-cassert</strong>) during the <span id="EN-US_TOPIC_0000001764491796__text1849355354">GaussDB(DWS)</span> compilation.</p>
<p id="EN-US_TOPIC_0000001764491796__p3525144812382"><strong id="EN-US_TOPIC_0000001764491796__b199081417114816">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__a5c21773f39c042cb835b4f663569eb78"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b10741640_14">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__u6772101d8fcd422fa6c6ce179713b431"><li id="EN-US_TOPIC_0000001764491796__l5cc38d58892f483a9f19e41c2ca0ae13"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b8423527069014_1">on</strong> indicates that various assertion checks are enabled.</li><li id="EN-US_TOPIC_0000001764491796__l00217b2f698a4277b4414e4ba8c4101c"><strong id="EN-US_TOPIC_0000001764491796__b2146935600142324">off</strong> indicates that various assertion checks are disabled.</li></ul>
<div class="note" id="EN-US_TOPIC_0000001764491796__n93f88db54a9d4822a6cf032ff50c1357"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><p id="EN-US_TOPIC_0000001764491796__abaf15f3c025546189c26b360fa2deaaf">This parameter is set to <strong id="EN-US_TOPIC_0000001764491796__b174881341185213">on</strong> by default if <span id="EN-US_TOPIC_0000001764491796__text1728374027">GaussDB(DWS)</span> is compiled with various assertion checks enabled.</p>
</div></div>
<p id="EN-US_TOPIC_0000001764491796__ad4809c6762fa43b8943cec963c7d184e"><strong id="EN-US_TOPIC_0000001764491796__b1223814775212">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b172386479524">off</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__sdca10fd86da9479bb6abb9dc88351c4e"><h4 class="sectiontitle">distribute_test_param</h4><p id="EN-US_TOPIC_0000001764491796__a78fb2f6bdaa24c15b964b10dcda864a4"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b8423527069226">Parameter description</strong>: Specifies whether the embedded test stubs for testing the distribution framework take effect. In most cases, developers embed some test stubs in the code during fault injection tests. Each test stub is identified by a unique name. The value of this parameter is a triplet that includes three values: thread level, test stub name, and error level of the injected fault. The three values are separated by commas (,).</p>
<p id="EN-US_TOPIC_0000001764491796__p62517586381"><strong id="EN-US_TOPIC_0000001764491796__b723722119481">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__a313f0b0ef5cc4845a77cbad60979c280"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b12382370659551">Value range</strong>: a string indicating the name of any embedded test stub.</p>
<p id="EN-US_TOPIC_0000001764491796__aadf6eba9f06b444f8ee9d8d80abd09cc"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b10614468999657">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b842352706144832">–1, default, default</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section118984511015"><h4 class="sectiontitle">ignore_checksum_failure</h4><p id="EN-US_TOPIC_0000001764491796__p4931245107"><strong id="EN-US_TOPIC_0000001764491796__b12518437412">Parameter description</strong>: Sets whether to ignore check failures (but still generates an alarm) and continues reading data. This parameter is valid only if <strong id="EN-US_TOPIC_0000001764491796__b11521553134520">enable_crc_check</strong> is set to <strong id="EN-US_TOPIC_0000001764491796__b1755303882311">on</strong>. Continuing reading data may result in breakdown, damaged data being transferred or hidden, failure of data recovery from remote nodes, or other serious problems. You are not advised to modify the settings.</p>
<p id="EN-US_TOPIC_0000001764491796__p13519161181519"><strong id="EN-US_TOPIC_0000001764491796__b09912210481">Type</strong>: SUSET</p>
<p id="EN-US_TOPIC_0000001764491796__p210512451804"><strong id="EN-US_TOPIC_0000001764491796__b741376348">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__ul51717251676"><li id="EN-US_TOPIC_0000001764491796__li18201253715"><strong id="EN-US_TOPIC_0000001764491796__b6208253064">on</strong> indicates that data check errors are ignored.</li><li id="EN-US_TOPIC_0000001764491796__li026202512717"><strong id="EN-US_TOPIC_0000001764491796__b156401023777">off</strong> indicates that data check errors are reported.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__p1611017458017"><strong id="EN-US_TOPIC_0000001764491796__b135124777">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b470352489">off</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section2998828382"><h4 class="sectiontitle">default_table_behavior</h4><p id="EN-US_TOPIC_0000001764491796__p499842810810"><strong id="EN-US_TOPIC_0000001764491796__b6104021488">Parameter description</strong>: behavior type of the default table. This parameter is supported only by clusters of version 8.2.1 or later.</p>
<p id="EN-US_TOPIC_0000001764491796__p1099810281989"><strong id="EN-US_TOPIC_0000001764491796__b1055838966">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p799811281681"><strong id="EN-US_TOPIC_0000001764491796__b1692736131319">Value range</strong>: <strong id="EN-US_TOPIC_0000001764491796__b86629411353">column_btree_index</strong>, <strong id="EN-US_TOPIC_0000001764491796__b101314436514">column_high_compress</strong>, <strong id="EN-US_TOPIC_0000001764491796__b15566164414515">column_middle_compress</strong>, or <strong id="EN-US_TOPIC_0000001764491796__b13708148857">column_low_compress</strong></p>
<ul id="EN-US_TOPIC_0000001764491796__ul162099190167"><li id="EN-US_TOPIC_0000001764491796__li15210191951620"><strong id="EN-US_TOPIC_0000001764491796__b9965151314362">column_btree_index</strong> indicates that the default index for creating a column-store table is <strong id="EN-US_TOPIC_0000001764491796__b17966141317365">btree</strong>.</li><li id="EN-US_TOPIC_0000001764491796__li3210161951619"><strong id="EN-US_TOPIC_0000001764491796__b7268522123619">column_high_compress</strong> indicates that the default compression level of column-store tables is <strong id="EN-US_TOPIC_0000001764491796__b1926822273617">high</strong>.</li><li id="EN-US_TOPIC_0000001764491796__li6210161981610"><strong id="EN-US_TOPIC_0000001764491796__b11378532143612">column_middle_compress</strong> indicates that the default compression level of column-store tables is <strong id="EN-US_TOPIC_0000001764491796__b2379133211367">middle</strong>.</li><li id="EN-US_TOPIC_0000001764491796__li1721011191163"><strong id="EN-US_TOPIC_0000001764491796__b5211143810364">column_low_compress</strong> indicates that the default compression level of column-store tables is <strong id="EN-US_TOPIC_0000001764491796__b112121238133611">low</strong>.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__p99988289810"><strong id="EN-US_TOPIC_0000001764491796__b199981281782">Default value</strong>: an empty string</p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__safc6199e99a24768a3e51a4a1188196b"><h4 class="sectiontitle">enable_colstore</h4><p id="EN-US_TOPIC_0000001764491796__ac11e112ae8384272a6a850092ec6e727"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b160434229691035">Parameter description</strong>: Specifies whether to create a table as a column-store table by default when no storage method is specified. The value for each node must be the same. This parameter is used for tests. Users are not allowed to enable it.</p>
<p id="EN-US_TOPIC_0000001764491796__p5993152731517"><strong id="EN-US_TOPIC_0000001764491796__b397242334813">Type</strong>: SUSET</p>
<p id="EN-US_TOPIC_0000001764491796__ab00ab4294e4d421686c015d02bfc8ea2"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b10741640_18">Value range</strong>: Boolean</p>
<p id="EN-US_TOPIC_0000001764491796__ab7daa137c4354b7caa72b473ff22836a"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b46080773_8">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b842352706145026">off</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section16321134218121"><h4 class="sectiontitle">enable_force_vector_engine</h4><p id="EN-US_TOPIC_0000001764491796__p143221142141211"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0085031973_en-us_topic_0059778871_en-us_topic_0058967732_b131980753891943">Parameter description</strong>: Specifies whether to forcibly generate vectorized execution plans for a vectorized execution operator if the operator's child node is a non-vectorized operator. When this parameter is set to <strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0085031973_b113821986314271">on</strong>, vectorized execution plans are forcibly generated. When <strong id="EN-US_TOPIC_0000001764491796__b43785211859">enable_force_vector_engine</strong> is enabled, no matter it is a row-store table, column-store table, or hybrid row-column store table, if the plantree does not contain scenarios that do not support vectorization, the vectorized executor is forcibly used.</p>
<p id="EN-US_TOPIC_0000001764491796__p10322194210123"><strong id="EN-US_TOPIC_0000001764491796__b99985101256">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p173221542121218"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b10741640_20">Value range</strong>: Boolean</p>
<p id="EN-US_TOPIC_0000001764491796__p1032374217126"><strong id="EN-US_TOPIC_0000001764491796__b1629419127518">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b1729412121350">off</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__saacf655a727c4c63bd3e1ee776dd00e6"><h4 class="sectiontitle">enable_csqual_pushdown</h4><p id="EN-US_TOPIC_0000001764491796__a93079ac4190c44db91acaf70333a3cc6"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b147714143392856">Parameter description</strong>: Specifies whether to deliver filter criteria for a rough check during query.</p>
<p id="EN-US_TOPIC_0000001764491796__p1421711434157"><strong id="EN-US_TOPIC_0000001764491796__b799814185910">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__a655332328fbd45a68fbb7c06ea4ca072"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b10741640_22">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__uac0f987951354354a341c15781ab8592"><li id="EN-US_TOPIC_0000001764491796__l1d1ca3de91d5434a9df370a8b8be4b7a"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b842352706152429">on</strong> indicates that a rough check is performed with filter criteria delivered during query.</li><li id="EN-US_TOPIC_0000001764491796__lf70d8ef42ace432b83236ca9aaf6a02f"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b131058467152452">off</strong> indicates that a rough check is performed without filter criteria delivered during query.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__a1a980e682a264e6798c7b45e3ee107a4"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b37941181103245_4">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b84235270614521">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__s3c82e3805aef453eab87dee4ab61190d"><h4 class="sectiontitle">explain_dna_file</h4><p id="EN-US_TOPIC_0000001764491796__a920efc122e2f4d2b8fe2ab08d6945c3b"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0085031973_en-us_topic_0059778871_en-us_topic_0058967732_b36485115993157">Parameter description</strong>: Specifies the name of a CSV file exported when <a href="#EN-US_TOPIC_0000001764491796__s16fe71bb07ef45c4b3119ee670eac7d1">explain_perf_mode</a> is set to <span class="parmvalue" id="EN-US_TOPIC_0000001764491796__en-us_topic_0085031973_en-us_topic_0059778871_en-us_topic_0058967732_parmvalue55512574493247"><b>run</b></span>.</p>
<p id="EN-US_TOPIC_0000001764491796__p104601227193913"><strong id="EN-US_TOPIC_0000001764491796__b28321824124810">Type</strong>: USERSET</p>
<div class="notice" id="EN-US_TOPIC_0000001764491796__n6e35156d88de447fbdac1a0bd8ab4771"><span class="noticetitle"><img src="public_sys-resources/notice_3.0-en-us.png"> </span><div class="noticebody"><p id="EN-US_TOPIC_0000001764491796__af356829a5ec947be8d02a791ac094ea7">The value of this parameter must be an absolute path plus a file name with the extension <strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b8423527069364">.csv</strong>.</p>
</div></div>
<p id="EN-US_TOPIC_0000001764491796__a6ce6fa006e2841dc9cb0bc7d5dd4be4b"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_a7f98c2d88a4543de9a6e560e8c359cf0">Value range</strong>: a string</p>
<p id="EN-US_TOPIC_0000001764491796__a60216fdefbfe4d10bf305ebb7b863813"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_afd123f4efdd44e96bd67b242ad5975da">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b842352706145423">NULL</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__s16fe71bb07ef45c4b3119ee670eac7d1"><a name="EN-US_TOPIC_0000001764491796__s16fe71bb07ef45c4b3119ee670eac7d1"></a><a name="s16fe71bb07ef45c4b3119ee670eac7d1"></a><h4 class="sectiontitle">explain_perf_mode</h4><p id="EN-US_TOPIC_0000001764491796__ada204358a8cb43658b2f5ae8b9a60139"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b149185851893626">Parameter description</strong>: Specifies the display format of the <strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b842352706142449">explain</strong> command.</p>
<p id="EN-US_TOPIC_0000001764491796__p4732143718393"><strong id="EN-US_TOPIC_0000001764491796__b10995524114812">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__aa9ee0691f9ed453cb9931d0aabdd34eb"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b214534291393731">Value range</strong>: <strong id="EN-US_TOPIC_0000001764491796__b842352706145456">normal</strong>, <strong id="EN-US_TOPIC_0000001764491796__b842352706145459">pretty</strong>, <strong id="EN-US_TOPIC_0000001764491796__b84235270614552">summary</strong>, and <strong id="EN-US_TOPIC_0000001764491796__b84235270614559">run</strong></p>
<ul id="EN-US_TOPIC_0000001764491796__u093b8fae322b4b11bcd2e4913fb303ab"><li id="EN-US_TOPIC_0000001764491796__l069780ebfeff4d30adcf489cb9a9ed50"><strong id="EN-US_TOPIC_0000001764491796__b3125164205312">normal</strong> indicates that the default printing format is used.</li><li id="EN-US_TOPIC_0000001764491796__l5bbc2899ea334ba6bd4219e61ff3a261"><strong id="EN-US_TOPIC_0000001764491796__b13579185105317">pretty</strong> indicates that the optimized display mode of <span id="EN-US_TOPIC_0000001764491796__text100928589">GaussDB(DWS)</span> is used. A new format contains a plan node ID, directly and effectively analyzing performance.</li><li id="EN-US_TOPIC_0000001764491796__lb7676c1e2daf456f96463360b93340bc"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b84235270693923">summary</strong> indicates that the analysis result based on such information is printed in addition to the printed information in the format specified by <strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_b404011371162013">pretty</strong>.</li><li id="EN-US_TOPIC_0000001764491796__le4bdfae778f1488faf3d91a8979ecf12"><strong id="EN-US_TOPIC_0000001764491796__b79458795514326">run</strong> indicates that in addition to the printed information specified by <strong id="EN-US_TOPIC_0000001764491796__b195065478014326">summary</strong>, the database exports the information as a CSV file.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__a3dbeabec56f34925be87f775ec668c63"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_ae87a28cece5946d8a210b66574ef37e4">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_b842352706151651">pretty</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section11450659472"><h4 class="sectiontitle">join_num_distinct</h4><p id="EN-US_TOPIC_0000001764491796__p114501559373"><strong id="EN-US_TOPIC_0000001764491796__b209528182714">Parameter description</strong>: Controls the default distinct value of the join column or expression in application scenarios.</p>
<p id="EN-US_TOPIC_0000001764491796__p1845011596717"><strong id="EN-US_TOPIC_0000001764491796__b201138599275">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p3450195911710"><strong id="EN-US_TOPIC_0000001764491796__b2561512162818">Value range</strong>: a double-precision floating point number greater than or equal to <strong id="EN-US_TOPIC_0000001764491796__b16359142411287">–100</strong>. Decimals may be truncated when displayed on clients.</p>
<ul id="EN-US_TOPIC_0000001764491796__ul31359317351"><li id="EN-US_TOPIC_0000001764491796__li14135831113518">If the value is greater than <strong id="EN-US_TOPIC_0000001764491796__b52078171298">0</strong>, the value is used as the default distinct value.</li><li id="EN-US_TOPIC_0000001764491796__li41361831143515">If the value is greater than or equal to <strong id="EN-US_TOPIC_0000001764491796__b1862173014293">–100</strong> and less than <strong id="EN-US_TOPIC_0000001764491796__b5831163517292">0</strong>, it means the percentage used to estimate the default distinct value.</li><li id="EN-US_TOPIC_0000001764491796__li1713613312355">If the value is <strong id="EN-US_TOPIC_0000001764491796__b48961198304">0</strong>, the default distinct value is <strong id="EN-US_TOPIC_0000001764491796__b0504125373011">200</strong>.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__p411396133015"><strong id="EN-US_TOPIC_0000001764491796__b19441124916719">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b44441491971">–20</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section462944015278"><h4 class="sectiontitle">outer_join_max_rows_multipler</h4><p id="EN-US_TOPIC_0000001764491796__p362914012276"><strong id="EN-US_TOPIC_0000001764491796__b191561122144914">Parameter description</strong>: Specifies the maximum number of estimated rows for outer joins.</p>
<p id="EN-US_TOPIC_0000001764491796__p162924042719"><strong id="EN-US_TOPIC_0000001764491796__b1338718413319">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p1629194019277"><strong id="EN-US_TOPIC_0000001764491796__b17380174318310">Value range</strong>: <strong id="EN-US_TOPIC_0000001764491796__b12116120414">0</strong> or a double-precision floating point number greater than or equal to <strong id="EN-US_TOPIC_0000001764491796__b1638020431732">1</strong>. Decimals may be truncated when displayed on clients.</p>
<ul id="EN-US_TOPIC_0000001764491796__ul262915406279"><li id="EN-US_TOPIC_0000001764491796__li12629124010272">If the value is <strong id="EN-US_TOPIC_0000001764491796__b3332214853">0</strong>, the estimated number of rows for outer joins is not limited.</li><li id="EN-US_TOPIC_0000001764491796__li962919408278">If the value is greater than or equal to <strong id="EN-US_TOPIC_0000001764491796__b162218611911">1</strong>, the estimated number of rows cannot exceed a multiple of the number of rows in the foreign table in the outer join.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__p362913408279"><strong id="EN-US_TOPIC_0000001764491796__b8320105217518">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b832111521520">1.1</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section1978024313357"><h4 class="sectiontitle">qual_num_distinct</h4><p id="EN-US_TOPIC_0000001764491796__p5780104303520"><strong id="EN-US_TOPIC_0000001764491796__b79031555143016">Parameter description</strong>: Controls the default distinct value of the filter column or expression in application scenarios.</p>
<p id="EN-US_TOPIC_0000001764491796__p77801243173512"><strong id="EN-US_TOPIC_0000001764491796__b48221805332">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p57801743143511"><strong id="EN-US_TOPIC_0000001764491796__b38130110596">Value range</strong>: a double-precision floating point number greater than or equal to <strong id="EN-US_TOPIC_0000001764491796__b1881414116598">–100</strong>. Decimals may be truncated when displayed on clients.</p>
<ul id="EN-US_TOPIC_0000001764491796__ul11102053123813"><li id="EN-US_TOPIC_0000001764491796__li2011015316386">If the value is greater than <strong id="EN-US_TOPIC_0000001764491796__b97899723312">0</strong>, the value is used as the default distinct value.</li><li id="EN-US_TOPIC_0000001764491796__li13110155343820">If the value is greater than or equal to <strong id="EN-US_TOPIC_0000001764491796__b15791115155917">–100</strong> and less than <strong id="EN-US_TOPIC_0000001764491796__b1679210555916">0</strong>, it means the percentage used to estimate the default distinct value.</li><li id="EN-US_TOPIC_0000001764491796__li71105531381">If the value is <strong id="EN-US_TOPIC_0000001764491796__b161991510143310">0</strong>, the default distinct value is <strong id="EN-US_TOPIC_0000001764491796__b8200710163319">200</strong>.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__p1178154363518"><strong id="EN-US_TOPIC_0000001764491796__b13687101183314">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b1668710117338">200</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__seea5c278b3cb4517b9030ac57cf721fa"><h4 class="sectiontitle">trace_notify</h4><p id="EN-US_TOPIC_0000001764491796__ad0058565f0774d41a562157eebdb16d2"><strong id="EN-US_TOPIC_0000001764491796__b21451213145310">Parameter description</strong>: Specifies whether to generate a large amount of debugging output for the <strong id="EN-US_TOPIC_0000001764491796__b18150161335311">LISTEN</strong> and <strong id="EN-US_TOPIC_0000001764491796__b915010137538">NOTIFY</strong> commands. <a href="dws_04_0915.html#EN-US_TOPIC_0000001811490985__sbd8ad9bb6b9b48ba97f998f060dc56f3">client_min_messages</a> or <a href="dws_04_0915.html#EN-US_TOPIC_0000001811490985__s1ffb0797361d413d875381200fed970b">log_min_messages</a> must be <strong id="EN-US_TOPIC_0000001764491796__b1265515175318">DEBUG1</strong> or lower so that such output can be recorded in the logs on the client or server separately.</p>
<p id="EN-US_TOPIC_0000001764491796__p11701165293915"><strong id="EN-US_TOPIC_0000001764491796__b189125266488">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__a3d3a8f42558a480291e75bc24995ef71"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b10741640_26">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__udbe6bc9bde1642aa9df7a003b7030abd"><li id="EN-US_TOPIC_0000001764491796__la5e43b7f057e4736958efc5fb94fa52e"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b84235270610156_1">on</strong> indicates that the function is enabled.</li><li id="EN-US_TOPIC_0000001764491796__lc779b16b9ba74116aa7ba4fa4a174094"><strong id="EN-US_TOPIC_0000001764491796__b58111847934350">off</strong> indicates that the function is disabled.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__a99607910666b4b8fbbaa9b003f6f6fce"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b46080773_14">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b8423527061523">off</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__s2d5c332082224e378f4ab7e2447dde6c"><h4 class="sectiontitle">trace_sort</h4><p id="EN-US_TOPIC_0000001764491796__a72413efd08da4a5bbb224838a824966a"><strong id="EN-US_TOPIC_0000001764491796__b165535402535">Parameter description</strong>: Specifies whether to display information about resource usage during sorting operations in logs. This parameter is available only when the macro TRACE_SORT is defined during the <span id="EN-US_TOPIC_0000001764491796__text1711948848">GaussDB(DWS)</span> compilation. However, TRACE_SORT is currently defined by default.</p>
<p id="EN-US_TOPIC_0000001764491796__p1361116320409"><strong id="EN-US_TOPIC_0000001764491796__b8554930104819">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__a595092a7dfe8471fad32cb17cbdd9c81"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b10741640_28">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__ue76d46acff23480981e797ae8e17a44d"><li id="EN-US_TOPIC_0000001764491796__l40c7c1bca6054f1ea307966adc9428cf"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b84235270610156_3">on</strong> indicates that the function is enabled.</li><li id="EN-US_TOPIC_0000001764491796__l1aeea7e0200d418882c9bd8505331d17"><strong id="EN-US_TOPIC_0000001764491796__b43140288934350">off</strong> indicates that the function is disabled.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__a2e0d4bd4f56e4d1e96559eeac3d1e88d"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b46080773_16">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b84235270615541">off</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__sfe7e2e59c9a545ecbc8e6aae628255ac"><h4 class="sectiontitle">zero_damaged_pages</h4><p id="EN-US_TOPIC_0000001764491796__a903015a56c2a45bb9819b02413963fbe"><strong id="EN-US_TOPIC_0000001764491796__b8785175014539">Parameter description</strong>: Specifies whether to detect a damaged page header that causes <span id="EN-US_TOPIC_0000001764491796__text1422231576">GaussDB(DWS)</span> to report an error, aborting the current transaction.</p>
<p id="EN-US_TOPIC_0000001764491796__p13276421169"><strong id="EN-US_TOPIC_0000001764491796__b157425301482">Type</strong>: SUSET</p>
<p id="EN-US_TOPIC_0000001764491796__a06a886b184d242928e16a3811ee3b0dc"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b10741640_42">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__ul171616272293"><li id="EN-US_TOPIC_0000001764491796__li14716327112917"><strong id="EN-US_TOPIC_0000001764491796__b1431922618">on</strong> indicates that the function is enabled.</li><li id="EN-US_TOPIC_0000001764491796__li6716162718295"><strong id="EN-US_TOPIC_0000001764491796__b33161310173315">off</strong> indicates that the function is disabled.</li></ul>
<div class="note" id="EN-US_TOPIC_0000001764491796__note187675162306"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><ul id="EN-US_TOPIC_0000001764491796__ul793511437383"><li id="EN-US_TOPIC_0000001764491796__li1593564312386">Setting this parameter to <strong id="EN-US_TOPIC_0000001764491796__b162192215337">on</strong> causes the system to report a warning, pad the damaged page with zeros, and then continue with subsequent processing. This behavior will damage data, that is, all rows on the damaged page. However, it allows you to bypass the error and retrieve rows from any undamaged pages that are present in the table. Therefore, it is useful for restoring data that is damaged due to a hardware or software error. In most cases, you are not advised to set this parameter to <strong id="EN-US_TOPIC_0000001764491796__b862974819334">on</strong> unless you do not want to restore data from the damaged pages of a table.</li><li id="EN-US_TOPIC_0000001764491796__li993519439381">For a column-store table, the system will skip the entire CU and then continue processing. The supported scenarios include the CRC check failure, magic check failure, and incorrect CU length.</li></ul>
</div></div>
<p id="EN-US_TOPIC_0000001764491796__a31bb8eb1deec43409023f1a70f523306"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b46080773_18">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b8423527061589">off</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__s9d3070772fd24cd9934d1eeca2d256c6"><h4 class="sectiontitle">replication_test</h4><p id="EN-US_TOPIC_0000001764491796__adf84caf229ad4a23b409f0bc26db68a2"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b842352706104549">Parameter description</strong>: Specifies whether to enable internal testing on the data replication function.</p>
<p id="EN-US_TOPIC_0000001764491796__p14302015154013"><strong id="EN-US_TOPIC_0000001764491796__b8971731134810">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__a1f3fb3921436422b8e4dfb5aac68f1c7"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b10741640_46">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__ue00e3ea19ad04007a7e4ffac846bc961"><li id="EN-US_TOPIC_0000001764491796__l2c7a7d601cc841a3adc38d04ecac2be9"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b842352706104648">on</strong> indicates that internal testing on the data replication function is enabled.</li><li id="EN-US_TOPIC_0000001764491796__lcecb176464604bf3b2c2e1c4ce61c5f6"><strong id="EN-US_TOPIC_0000001764491796__b46635984134350">off</strong> indicates that internal testing on the data replication function is disabled.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__ae8f36833116146f68fddda2d230cb0d8"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b46080773_22">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b842352706151612">off</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__s4aa885c181c4403d9942e6951aa67a17"><h4 class="sectiontitle">cost_param</h4><p id="EN-US_TOPIC_0000001764491796__ac27c311ccb834b2f966df3ebc722fffd"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b21094962111229">Parameter description</strong>: Controls use of different estimation methods in specific customer scenarios, allowing estimated values approximating to onsite values. This parameter can control various methods simultaneously by performing AND (&amp;) operations on the bit for each method. A method is selected if its value is not <span class="parmvalue" id="EN-US_TOPIC_0000001764491796__parmvalue2077304747144331"><b>0</b></span>.</p>
<p id="EN-US_TOPIC_0000001764491796__a6fc66e66f8eb46a9844fa2f99e2fc6e8">If <strong id="EN-US_TOPIC_0000001764491796__b1552103724718">cost_param &amp; 1</strong> is not set to <strong id="EN-US_TOPIC_0000001764491796__b1355293764712">0</strong>, an improvement mechanism is selected for calculating a non-equi join selection rate, which is more accurate in estimation of self-join (join between two same tables). In <span id="EN-US_TOPIC_0000001764491796__ph13267135293517">V300R002C00</span> and later, <strong id="EN-US_TOPIC_0000001764491796__b2552103754717">cost_param &amp; 1=0</strong> is not used. That is, an optimized formula is selected for calculation.</p>
<p id="EN-US_TOPIC_0000001764491796__a7d3d193f73da479abe8fad983eb097fa">When <span class="parmname" id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_parmname936426231111154"><b>cost_param &amp; 2</b></span> is set to a value other than <span class="parmvalue" id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_parmvalue1835860841111154"><b>0</b></span>, the selection rate is estimated based on multiple filter criteria. The lowest selection rate among all filter criteria, but not the product of the selection rates for two tables under a specific filter criterion, is used as the total selection rate. This method is more accurate when a close correlation exists between the columns to be filtered.</p>
<p id="EN-US_TOPIC_0000001764491796__ad34263dc0c2b4bd8a2bcf217cd0c9120">When <span class="parmname" id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_parmname1158438200155445"><b>cost_param &amp; 4</b></span> is not <span class="parmvalue" id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_parmvalue35083637155445"><b>0</b></span>, the selected debugging model is not recommended when the stream node is evaluated.</p>
<p id="EN-US_TOPIC_0000001764491796__p121521152191317">When <strong id="EN-US_TOPIC_0000001764491796__b13103191310334">cost_param &amp; 16</strong> is not <strong id="EN-US_TOPIC_0000001764491796__b61031139337">0</strong>, the model between fully correlated and fully uncorrelated models is used to calculate the comprehensive selection rate of two or more filtering conditions or join conditions. If there are many filtering conditions, the strongly-correlated model is preferred.</p>
<p id="EN-US_TOPIC_0000001764491796__p1269972410403"><strong id="EN-US_TOPIC_0000001764491796__b0273133174812">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__ab3f933e58fae41a684549d0a2d025f5e"><strong id="EN-US_TOPIC_0000001764491796__b72064000734350">Value range</strong>: an integer ranging from 1 to INT_MAX</p>
<p id="EN-US_TOPIC_0000001764491796__ad310eaf261de418c8bc1ccf1e3590774"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b61650132_6">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b842352706151931">16</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__s52ddbced6d054fa8aef56b60f4d83850"><h4 class="sectiontitle">convert_string_to_digit</h4><p id="EN-US_TOPIC_0000001764491796__add8460437caa4e1b860dd295b6a76549"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b8423527069283">Parameter description</strong>: Specifies the implicit conversion priority, which determines whether to preferentially convert strings into numbers.</p>
<p id="EN-US_TOPIC_0000001764491796__p1350893218405"><strong id="EN-US_TOPIC_0000001764491796__b114691631114812">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__a0b6aa021700240149ad31ccf53ac8370"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b10741640_48">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__u544a6347e9284295891557791ff71585"><li id="EN-US_TOPIC_0000001764491796__lba07d29043624f8a90b6aad96f09bbf3"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b84235270611217">on</strong> indicates that strings are preferentially converted into numbers.</li><li id="EN-US_TOPIC_0000001764491796__lab36125a2834442d8f99dcdf4b6fa107"><strong id="EN-US_TOPIC_0000001764491796__b1415687635144819">off</strong> indicates that strings are not preferentially converted into numbers.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__ad94a0abb0cac42e7b2cf0e330106c52c"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b6125520212036_2">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b842352706152029">on</strong></p>
<div class="notice" id="EN-US_TOPIC_0000001764491796__note6967113133211"><span class="noticetitle"><img src="public_sys-resources/notice_3.0-en-us.png"> </span><div class="noticebody"><p id="EN-US_TOPIC_0000001764491796__p14903530173011">Modify this parameter only when absolutely necessary because the modification will change the rule for converting internal data types and may cause unexpected results.</p>
</div></div>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__s91876ad6d74646e7a825d6dd447667bc"><h4 class="sectiontitle">nls_timestamp_format</h4><p id="EN-US_TOPIC_0000001764491796__a06f00dc9eb1641d0b4c752146bdb92a0"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b842352706112137">Parameter description</strong>: Specifies the default timestamp format.</p>
<p id="EN-US_TOPIC_0000001764491796__p79051641114011"><strong id="EN-US_TOPIC_0000001764491796__b1866711312481">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__af76c48dd086c4fb089c7fec49464823e"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b842352706112225">Value range</strong>: a string</p>
<p id="EN-US_TOPIC_0000001764491796__ad4a6fec483524244bac6fc7e3ecc4aab"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b1912033555112237">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b84235270615213">DD-Mon-YYYY HH:MI:SS.FF AM</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__s6e188648d0ad413e871dde5c185c2821"><h4 class="sectiontitle">enable_partitionwise</h4><p id="EN-US_TOPIC_0000001764491796__a725220629e1f40cf8e4b627c7baff6c0"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b842352706112523">Parameter description</strong>: Specifies whether to select an intelligent algorithm for joining partitioned tables.</p>
<p id="EN-US_TOPIC_0000001764491796__p6912155034013"><strong id="EN-US_TOPIC_0000001764491796__b64053244818">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__a576f749f40c8416a8675eced33f96506"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b16754081162213">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__u7eb29a6f0a0040f69fdcdf8112f59a75"><li id="EN-US_TOPIC_0000001764491796__l548a63a599144a479b542a2ced0b81d7"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b84235270611276_1">on</strong> indicates that an intelligent algorithm is selected.</li><li id="EN-US_TOPIC_0000001764491796__lb9fa7b3aa3c64a3eb7f39f066da0d234"><strong id="EN-US_TOPIC_0000001764491796__b134815161714501">off</strong> indicates that an intelligent algorithm is not selected.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__aafac74f2668743c2b101c784e55ea422"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b46080773_24">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b84235270615255">off</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section825595755117"><h4 class="sectiontitle">enable_partition_dynamic_pruning</h4><p id="EN-US_TOPIC_0000001764491796__p525535714517"><strong id="EN-US_TOPIC_0000001764491796__b163961109401">Parameter description</strong>: Specifies whether dynamic pruning is enabled during partition table scanning.</p>
<p id="EN-US_TOPIC_0000001764491796__p9256125719513"><strong id="EN-US_TOPIC_0000001764491796__b158917131409">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p19256957145111"><strong id="EN-US_TOPIC_0000001764491796__b28402149409">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__ul20256125745112"><li id="EN-US_TOPIC_0000001764491796__li132566572517"><strong id="EN-US_TOPIC_0000001764491796__b583118589402">on</strong>: enable</li><li id="EN-US_TOPIC_0000001764491796__li16233214535"><strong id="EN-US_TOPIC_0000001764491796__b1624741314418">off</strong>: disable</li></ul>
<p id="EN-US_TOPIC_0000001764491796__p1625615710515"><strong id="EN-US_TOPIC_0000001764491796__b1780991620413">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b5809216114110">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__s52a0656d4aec461aa208616489c3362e"><h4 class="sectiontitle">max_user_defined_exception</h4><p id="EN-US_TOPIC_0000001764491796__a5c4f50ae7d464a34a00ade1763814b9c"><strong id="EN-US_TOPIC_0000001764491796__b14891351193213">Parameter description</strong>: Specifies the maximum number of exceptions. The default value cannot be changed.</p>
<p id="EN-US_TOPIC_0000001764491796__p235751194111"><strong id="EN-US_TOPIC_0000001764491796__b420373218482">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__ad1202fa17a6349d191c902d012435006"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_a7a9cc0fdf8de40779cb11862ef669066">Value range</strong>: an integer</p>
<p id="EN-US_TOPIC_0000001764491796__a5a6a6c0f95eb4fda9c6b672ee87ed975"><strong id="EN-US_TOPIC_0000001764491796__b77447017616429">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b3061407016429">1000</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__s33ef66a4cb9843db922428a5e4107da1"><h4 class="sectiontitle">datanode_strong_sync</h4><p id="EN-US_TOPIC_0000001764491796__ab71d3f548d9348baa3709158e6b74fc7"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_b842352706102047">Parameter description</strong>: This parameter no longer takes effect.</p>
<p id="EN-US_TOPIC_0000001764491796__p197854824118"><strong id="EN-US_TOPIC_0000001764491796__b12387163217489">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__aef4aa244b4524b7b981b5e42916ad245"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_a65b7a7d09251449ea6605549c1c34541">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__uf61ed5cfe5d247079b8cafd4c8ff7903"><li id="EN-US_TOPIC_0000001764491796__lea2fb4e2d630424d92ef0590da659b69"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b842352706113332_1">on</strong> indicates that forcible synchronization between stream nodes is enabled.</li><li id="EN-US_TOPIC_0000001764491796__l18e953a1a6ab44f8883ba6e23bc46213"><strong id="EN-US_TOPIC_0000001764491796__b629721023145053">off</strong> indicates that forcible synchronization between stream nodes is disabled.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__a43e0af6a595b4932a33c11011533dda9"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b46080773_26">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b842352706152730">off</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__s46971fbae49a4605b3348ad268c7320b"><h4 class="sectiontitle">enable_global_stats</h4><p id="EN-US_TOPIC_0000001764491796__acd79fb5be55b490b95e00881010673a9"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b84235270613582">Parameter description</strong>: Specifies the current statistics mode. This parameter is used to compare global statistics generation plans and the statistics generation plans for a single DN. This parameter is used for tests. Users are not allowed to enable it.</p>
<p id="EN-US_TOPIC_0000001764491796__p9556100111710"><strong id="EN-US_TOPIC_0000001764491796__b1997043219485">Type</strong>: SUSET</p>
<p id="EN-US_TOPIC_0000001764491796__abe4f6a24b4434f3886fcae840ea031cf"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b10741640_52">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__u3b451e5a0ad745ca875bd9d7dec98b6c"><li id="EN-US_TOPIC_0000001764491796__l78f288fb5d1148e19d2f25b10c954c25"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b84235270614149">on</strong> or <strong id="EN-US_TOPIC_0000001764491796__b10621205113217">true</strong> indicates the global statistics mode.</li><li id="EN-US_TOPIC_0000001764491796__ld4504674b7cf4c1e9deb28525d0d7c7a"><strong id="EN-US_TOPIC_0000001764491796__b1774956203214">off</strong> or <strong id="EN-US_TOPIC_0000001764491796__b1019911373319">false</strong> indicates the single-DN statistics mode.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__a7eca7c6c52744a2fa62907340a5e5de0"><strong id="EN-US_TOPIC_0000001764491796__b606780654">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b1546800902">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__sdf986a27d14a4eeca7a85218bb0d70fc"><h4 class="sectiontitle">enable_fast_numeric</h4><p id="EN-US_TOPIC_0000001764491796__a20da9895edff4e28b9274ae3dfc1f2ab"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b84235270614311">Parameter description</strong>: Specifies whether to enable optimization for numeric data calculation. Calculation of numeric data is time-consuming. Numeric data is converted into int64- or int128-type data to improve numeric data calculation performance.</p>
<p id="EN-US_TOPIC_0000001764491796__p630411205416"><strong id="EN-US_TOPIC_0000001764491796__b1610813317485">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__ac99cce35f9e940ffb06b531e5dcf68cb"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b10741640_54">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__ud15e56a590934f88ac221ac4fcb815fe"><li id="EN-US_TOPIC_0000001764491796__lc0db949573864e7db7a305c4e77e1c8b"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b84235270614345">on/true</strong> indicates that optimization for numeric data calculation is enabled.</li><li id="EN-US_TOPIC_0000001764491796__l032a62540eb84f518adea91e01548fa6"><strong id="EN-US_TOPIC_0000001764491796__b1227554481145544">off/false</strong> indicates that optimization for numeric data calculation is disabled.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__a334385cff15647fabe235abf8e4d710f"><strong id="EN-US_TOPIC_0000001764491796__b773646050">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b1589541769">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section1731164732612"><h4 class="sectiontitle">enable_row_fast_numeric</h4><p id="EN-US_TOPIC_0000001764491796__p1631114712614"><strong id="EN-US_TOPIC_0000001764491796__b3501545134515">Parameter description</strong>: Specifies the format in which numeric data in a row-store table is spilled to disks.</p>
<p id="EN-US_TOPIC_0000001764491796__p53111247192616"><strong id="EN-US_TOPIC_0000001764491796__b1191175114446">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p731112479265"><strong id="EN-US_TOPIC_0000001764491796__b15256145319442">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__ul19311114713266"><li id="EN-US_TOPIC_0000001764491796__li1431114475263"><strong id="EN-US_TOPIC_0000001764491796__b17743132911498">on/true</strong> indicates that numeric data in a row-store table is spilled to disks in bigint format.</li><li id="EN-US_TOPIC_0000001764491796__li1131184762613"><strong id="EN-US_TOPIC_0000001764491796__b944417154503">off/false</strong> indicates that numeric data in a row-store table is spilled to disks in the original format.</li></ul>
<div class="notice" id="EN-US_TOPIC_0000001764491796__note1086416237362"><span class="noticetitle"><img src="public_sys-resources/notice_3.0-en-us.png"> </span><div class="noticebody"><p id="EN-US_TOPIC_0000001764491796__p1828141410376">If this parameter is set to <strong id="EN-US_TOPIC_0000001764491796__b8335203255815">on</strong>, you are advised to enable <strong id="EN-US_TOPIC_0000001764491796__b1759964695917">enable_force_vector_engine</strong> to improve the query performance of large data sets. However, compared with the original format, there is a high probability that the bigint format occupies more disk space. For example, the TPC-H test set occupies about 7% more space (reference value, may vary depending on the environment).</p>
</div></div>
<p id="EN-US_TOPIC_0000001764491796__p10864102373617"><strong id="EN-US_TOPIC_0000001764491796__b26712713451">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b177415271451">off</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__s333914ac6c8f4cd4a6ce9ed73bb2be14"><h4 class="sectiontitle">rewrite_rule</h4><p id="EN-US_TOPIC_0000001764491796__aadb206b6e06144aba4dc5a86a46b8b54"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_b84235270695334">Parameter description</strong>: Specifies the rewriting rule for enabled optional queries. Some query rewriting rules are optional. Enabling them cannot always improve query efficiency. In a specific customer scenario, you can set the query rewriting rules through the GUC parameter to achieve optimal query efficiency.</p>
<p id="EN-US_TOPIC_0000001764491796__acff5283804694eb0bff3536e253f5257">This parameter can control the combination of query rewriting rules, for example, there are multiple rewriting rules: rule1, rule2, rule3, and rule4. To set the parameters, you can perform the following operations:</p>
<pre class="codeblock" id="EN-US_TOPIC_0000001764491796__c0f33646897a847c78b97cc954edd6337">set rewrite_rule=rule1; --Enable query rewriting rule rule1.
set rewrite_rule=rule2,rule3; --Enable query rewriting rules rule2 and rule3.
set rewrite_rule=none; --Disable all optional query rewriting rules.</pre>
<p id="EN-US_TOPIC_0000001764491796__p1698152934113"><strong id="EN-US_TOPIC_0000001764491796__b8351935194812">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__a3d8c820d08c0489ba6c10a47476f8b23"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_b44366800195127">Value range</strong>: a string</p>
<ul id="EN-US_TOPIC_0000001764491796__u582a49208d014b459af16e68a402d6df"><li id="EN-US_TOPIC_0000001764491796__l809bf5bea254485d9ac4dc25947b5c18"><strong id="EN-US_TOPIC_0000001764491796__b1895513546515">none</strong>: No optional query rewrite rules are used.</li><li id="EN-US_TOPIC_0000001764491796__l23cd64e035524005929848d0127b3d8e"><strong id="EN-US_TOPIC_0000001764491796__b444511231879">Lazyagg</strong>: The Lazy Agg query rewrite rule is used to eliminate aggregate operations in subqueries.</li><li id="EN-US_TOPIC_0000001764491796__li17831429124620"><strong id="EN-US_TOPIC_0000001764491796__b2014619511777">magicset</strong>: The Magic Set query rewrite rule is used to push conditions from the main query down to promoted sublinks.</li><li id="EN-US_TOPIC_0000001764491796__li15390132510245"><strong id="EN-US_TOPIC_0000001764491796__b341618591175">uniquecheck</strong>: Uses the Unique Check rewriting rule. (The scenario where the target column does not contain the expression sublink of the aggregate function can be improved. The function can be enabled only when the value of the target column is unique after the sublink is aggregated based on the associated column. This function is recommended to be used by optimization engineers.)</li><li id="EN-US_TOPIC_0000001764491796__li13943144817253"><strong id="EN-US_TOPIC_0000001764491796__b1087431310418">disablerep</strong>: Uses the function that prohibits pulling up sublinks of the replication table. (Disables sublink pull-up for the replication table.)</li><li id="EN-US_TOPIC_0000001764491796__li7688122815254"><strong id="EN-US_TOPIC_0000001764491796__b422311145014">projection_pushdown</strong>: the Projection Pushdown rewriting rule (Removes columns that are not used by the parent query from the subquery).</li><li id="EN-US_TOPIC_0000001764491796__li8495140161518"><strong id="EN-US_TOPIC_0000001764491796__b2790175645219">or_conversion</strong>: the OR conversion rewriting rule (eliminates the association OR conditions that are inefficient to execute).</li><li id="EN-US_TOPIC_0000001764491796__li979194110245"><strong id="EN-US_TOPIC_0000001764491796__b188862021161116">plain_lazyagg</strong>: the <strong id="EN-US_TOPIC_0000001764491796__b73171400125">Plain Lazy Agg</strong> query rewriting rule (eliminates aggregation operations in a single subquery). This option is supported only by clusters of version 8.1.3.100 or later.</li><li id="EN-US_TOPIC_0000001764491796__li46910011512"><strong id="EN-US_TOPIC_0000001764491796__b933316715567">eager_magicset</strong>: Uses the <strong id="EN-US_TOPIC_0000001764491796__b17210131917568">eager_magicset</strong> query rewriting rule (to push down conditions from the main query to subqueries). This option is supported only by clusters of version 8.2.0 or later.</li><li id="EN-US_TOPIC_0000001764491796__li32073205186"><strong id="EN-US_TOPIC_0000001764491796__b176211862086">casewhen_simplification</strong>: This rewrite rule uses the <strong id="EN-US_TOPIC_0000001764491796__b191124319914">CASE WHEN</strong> statement to simplify queries. When enabled, it rewrites <strong id="EN-US_TOPIC_0000001764491796__b16903111410102">(case when xxx then const1 else const2)=const1</strong>. This option is supported only by clusters of version 8.3.0 or later.</li><li id="EN-US_TOPIC_0000001764491796__li3325348552"><strong id="EN-US_TOPIC_0000001764491796__b10412616131218">outer_join_quality_imply</strong>: When there is an equi-join condition between a left outer join and a right outer join, this rule pushes the expression condition on the outer table's join column down to the inner table's join column. This option is supported only by clusters of version 8.3.0 or later.</li><li id="EN-US_TOPIC_0000001764491796__li9476154814122"><strong id="EN-US_TOPIC_0000001764491796__b37153411217">inlist_merge</strong>: This query rewrite rule uses the <strong id="EN-US_TOPIC_0000001764491796__b4465350181212">inlist_or_inlist</strong> method to merge <strong id="EN-US_TOPIC_0000001764491796__b9371131131313">OR</strong> statements with the same base table column. When enabled, it merges and rewrites <strong id="EN-US_TOPIC_0000001764491796__b871010841314">(where a in (list1) or a in (list2))</strong> to support <strong id="EN-US_TOPIC_0000001764491796__b10370101411320">inlist2join</strong>. This option is supported only by clusters of version 8.3.0 or later.</li><li id="EN-US_TOPIC_0000001764491796__li09921058185612"><strong id="EN-US_TOPIC_0000001764491796__b189111932201315">subquery_qual_pull_up</strong>: For subqueries that cannot be promoted, if the subquery has filtering conditions on columns that are also used for joining with other tables, this rule extracts the filtering conditions from the subquery and passes them to the other side of the join condition. Currently, only <strong id="EN-US_TOPIC_0000001764491796__b8847762143">var op const</strong> forms without type conversion, such as <strong id="EN-US_TOPIC_0000001764491796__b1926518126147">a &gt; 2</strong>, are supported. When enabled, it is assumed that <strong id="EN-US_TOPIC_0000001764491796__b749802911143">outer_join_quality_imply</strong> is also enabled. This is supported only by clusters of version 9.1.0 or later.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__a97c28ae246e3464aa63de98c910603c4"><strong id="EN-US_TOPIC_0000001764491796__acbfbfc0a61ee409fa994029a647ad4a4">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b960816424145">magicset</strong>, <strong id="EN-US_TOPIC_0000001764491796__b92944414140">or_conversion</strong>, <strong id="EN-US_TOPIC_0000001764491796__b15543945201415">projection_pushdown</strong>, <strong id="EN-US_TOPIC_0000001764491796__b129211646111412">plain_lazyagg</strong>, or <strong id="EN-US_TOPIC_0000001764491796__b890314482142">subquery_qual_pull_up</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section1683821583115"><h4 class="sectiontitle">mv_rewrite_rule</h4><p id="EN-US_TOPIC_0000001764491796__p2838181523112"><strong id="EN-US_TOPIC_0000001764491796__b19838163319417">Parameter description</strong>: whether to enable the rewriting rule for the materialized view.</p>
<p id="EN-US_TOPIC_0000001764491796__p14838415163120"><strong id="EN-US_TOPIC_0000001764491796__b30908132">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p2838815113119"><strong id="EN-US_TOPIC_0000001764491796__b78381415173117">Value range</strong>: a string</p>
<ul id="EN-US_TOPIC_0000001764491796__ul083814159319"><li id="EN-US_TOPIC_0000001764491796__li14838315113120"><strong id="EN-US_TOPIC_0000001764491796__b131395331639">none</strong>: No materialized view rewriting rule is used. This value is available only in clusters of version 8.2.1.100 or later.</li><li id="EN-US_TOPIC_0000001764491796__li383841514313"><strong id="EN-US_TOPIC_0000001764491796__b878186338">text</strong>: materialized view rewriting rule that uses text matching. This value is available only in clusters of version 8.2.1.100 or later.</li><li id="EN-US_TOPIC_0000001764491796__li211133422311"><strong id="EN-US_TOPIC_0000001764491796__b28091023124516">general</strong>: indicates whether to enable structure matching. This value is supported only by 9.1.0.200 and later cluster versions.</li><li id="EN-US_TOPIC_0000001764491796__li962511501659"><strong id="EN-US_TOPIC_0000001764491796__b8362123815372">predicate</strong>: specifies whether to enable the expression framework for structure matching rewriting. This parameter is used for preprocessing and regularization of filter and association conditions. This parameter takes effect only when <strong id="EN-US_TOPIC_0000001764491796__b1681325193712">general</strong> is enabled. This value is supported only by 9.1.0.210 and later cluster versions.</li><li id="EN-US_TOPIC_0000001764491796__li12268561053"><strong id="EN-US_TOPIC_0000001764491796__b3279154823715">view_delta</strong>: indicates whether to use the primary and foreign key relationships to eliminate redundant joins in materialized views and then match the materialized views with queries. This value is supported only by 9.1.0.210 and later cluster versions.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__p1719514118320"><strong id="EN-US_TOPIC_0000001764491796__b2367152163818">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b1229172473818">text</strong>, <strong id="EN-US_TOPIC_0000001764491796__b14885122673819">general</strong>, and <strong id="EN-US_TOPIC_0000001764491796__b10111529133812">predicate</strong></p>
<div class="notice" id="EN-US_TOPIC_0000001764491796__note1118831415232"><span class="noticetitle"><img src="public_sys-resources/notice_3.0-en-us.png"> </span><div class="noticebody"><p id="EN-US_TOPIC_0000001764491796__p18620103542317"><strong id="EN-US_TOPIC_0000001764491796__b15505184033817">general</strong>, <strong id="EN-US_TOPIC_0000001764491796__b6478184223816">predicate</strong>, and <strong id="EN-US_TOPIC_0000001764491796__b12854523816">view_delta</strong> are restricted for commercial use. To use them, contact technical support.</p>
</div></div>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__s3fe7f177cf2d42d091881dae6a3c9af7"><h4 class="sectiontitle">enable_compress_spill</h4><p id="EN-US_TOPIC_0000001764491796__aa99d2376a98c4f6bb9845a2f805ae184"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967586_b842352706193513_1">Parameter description</strong>: Specifies whether to enable the compression function of writing data to a disk.</p>
<p id="EN-US_TOPIC_0000001764491796__p194476377415"><strong id="EN-US_TOPIC_0000001764491796__b13527133512487">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__a26e8b3ac5a6f44faa01851a91eb084bd"><strong id="EN-US_TOPIC_0000001764491796__b209791372114586">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_ul16131530193"><li id="EN-US_TOPIC_0000001764491796__l92ff8d0ab3874868b1f9b4437b288f1b"><strong id="EN-US_TOPIC_0000001764491796__b1235548773145816">on/true</strong> indicates that optimization for writing data to a disk is enabled.</li><li id="EN-US_TOPIC_0000001764491796__la5c9c3e7b8c9454ab4f5cc71c6ff8f8a"><strong id="EN-US_TOPIC_0000001764491796__b255718568145822">off/false</strong> indicates that optimization for writing data to a disk is disabled.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__a1b077fc8586c414290d396164ed37aed"><strong id="EN-US_TOPIC_0000001764491796__b1754121638">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b1045671807">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section41951721291"><h4 class="sectiontitle">analysis_options</h4><p id="EN-US_TOPIC_0000001764491796__p2195428918"><strong id="EN-US_TOPIC_0000001764491796__b149271955171419">Parameter description</strong>: Specifies whether to enable corresponding features, such as data validation and performance statistics.</p>
<p id="EN-US_TOPIC_0000001764491796__p863484684112"><strong id="EN-US_TOPIC_0000001764491796__b2083903584818">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p3195621496"><strong id="EN-US_TOPIC_0000001764491796__b14018944">Value range</strong>: a string</p>
<ul id="EN-US_TOPIC_0000001764491796__ul111951521891"><li id="EN-US_TOPIC_0000001764491796__li61956217916"><strong id="EN-US_TOPIC_0000001764491796__b163371427101915">LLVM_COMPILE</strong> indicates that the codegen compilation time of each thread is displayed on the explain performance page.</li><li id="EN-US_TOPIC_0000001764491796__li91951721794"><strong id="EN-US_TOPIC_0000001764491796__b174461305196">HASH_CONFLICT</strong> indicates that the log file in the <strong id="EN-US_TOPIC_0000001764491796__b11446133011196">pg_log</strong> directory of the DN process displays the hash table statistics, including the hash table size, hash chain length, and hash conflict information.</li><li id="EN-US_TOPIC_0000001764491796__li71958211919"><strong id="EN-US_TOPIC_0000001764491796__b20986113416197">STREAM_DATA_CHECK</strong> indicates that a CRC check is performed on data before and after network data transmission.</li><li id="EN-US_TOPIC_0000001764491796__li11844512183210"><strong id="EN-US_TOPIC_0000001764491796__b16986937181916">TURBO_DATA_CHECK</strong> indicates that the data context of the <strong id="EN-US_TOPIC_0000001764491796__b19877371192">ScalarVector</strong> and <strong id="EN-US_TOPIC_0000001764491796__b49881377194">VectorBatch</strong> operators of Turbo is verified. This parameter is supported only by clusters of version 8.3.0.100 or later.</li><li id="EN-US_TOPIC_0000001764491796__li18377125115614"><strong id="EN-US_TOPIC_0000001764491796__b135578586201">KEEP_SAMPLE_DATA</strong>: This parameter retains the sampling data used in each analyze operation in the form of temporary tables. This parameter is supported only by clusters of version 9.1.0 or later.</li><li id="EN-US_TOPIC_0000001764491796__li1539383010547"><strong id="EN-US_TOPIC_0000001764491796__b1524718282219">BLOCK_RULE</strong>: indicates that the time required for checking the query filter is displayed on the explain performance page. This is supported only by 9.1.0.100 and later cluster versions.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__p131951321696"><strong id="EN-US_TOPIC_0000001764491796__b842352706155055">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b84235270615511">off(ALL)</strong>, which indicates that no location function is enabled.</p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section11914205152413"><h4 class="sectiontitle">resource_track_log</h4><p id="EN-US_TOPIC_0000001764491796__p9913551132418"><strong id="EN-US_TOPIC_0000001764491796__b16778194335712">Parameter description</strong>: Specifies the log level of self-diagnosis. Currently, this parameter takes effect only in multi-column statistics.</p>
<p id="EN-US_TOPIC_0000001764491796__p1330625614415"><strong id="EN-US_TOPIC_0000001764491796__b14263610486">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p169144514243"><strong id="EN-US_TOPIC_0000001764491796__b308539354">Value range</strong>: a string</p>
<ul id="EN-US_TOPIC_0000001764491796__ul191425192419"><li id="EN-US_TOPIC_0000001764491796__li69141751142416"><strong id="EN-US_TOPIC_0000001764491796__b20566248112">summary</strong>: Brief diagnosis information is displayed.</li><li id="EN-US_TOPIC_0000001764491796__li24317516439"><strong id="EN-US_TOPIC_0000001764491796__b362619271127">detail</strong>: Detailed diagnosis information is displayed.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__p925966104415">Currently, the two parameter values differ only when there is an alarm about multi-column statistics not collected. If the parameter is set to <strong id="EN-US_TOPIC_0000001764491796__b124677321226">summary</strong>, such an alarm will not be displayed. If it is set to <strong id="EN-US_TOPIC_0000001764491796__b1446813327219">detail</strong>, such an alarm will be displayed.</p>
<p id="EN-US_TOPIC_0000001764491796__p159147518249"><strong id="EN-US_TOPIC_0000001764491796__b114989281635">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b05001328134">summary</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section189901634112519"><h4 class="sectiontitle">hll_default_log2m</h4><p id="EN-US_TOPIC_0000001764491796__p152961221141812"><strong id="EN-US_TOPIC_0000001764491796__b14594144910312">Parameter description</strong>: Specifies the number of buckets for HLL data. The number of buckets affects the precision of distinct values calculated by HLL. As the number of buckets increases, the deviation becomes smaller. The deviation range is as follows: [–1.04/2<sup id="EN-US_TOPIC_0000001764491796__sup196621119142218">log2m*1/2</sup>, +1.04/2<sup id="EN-US_TOPIC_0000001764491796__sup393323972211">log2m*1/2</sup>]</p>
<p id="EN-US_TOPIC_0000001764491796__p199931419425"><strong id="EN-US_TOPIC_0000001764491796__b72136363486">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p899133412256"><strong id="EN-US_TOPIC_0000001764491796__b899153442514">Value range</strong>: an integer ranging from 10 to 16</p>
<p id="EN-US_TOPIC_0000001764491796__p199912348251"><strong id="EN-US_TOPIC_0000001764491796__b8651523192616">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b42794364267">11</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section185791437112511"><h4 class="sectiontitle">hll_default_regwidth</h4><p id="EN-US_TOPIC_0000001764491796__p658015377251"><strong id="EN-US_TOPIC_0000001764491796__b34591158172618">Parameter description</strong>: Specifies the number of bits in each bucket for HLL data. A larger value indicates more memory occupied by HLL. <strong id="EN-US_TOPIC_0000001764491796__b165038491142">hll_default_regwidth</strong> and <strong id="EN-US_TOPIC_0000001764491796__b6531754111414">hll_default_log2m</strong> determine the maximum number of distinct values that can be calculated by HLL. For details, see <a href="#EN-US_TOPIC_0000001764491796__table05450516616">Table 1</a>.</p>
<p id="EN-US_TOPIC_0000001764491796__p186012144420"><strong id="EN-US_TOPIC_0000001764491796__b037233612488">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p20580173732518"><strong id="EN-US_TOPIC_0000001764491796__b155801637182513">Value range</strong>: an integer ranging from 1 to 5</p>
<p id="EN-US_TOPIC_0000001764491796__p1258016372256"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059779078_a5e8289e264814e01800c00b0d832c9e4">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b842352706162730">5</strong></p>
<div class="tablenoborder"><a name="EN-US_TOPIC_0000001764491796__table05450516616"></a><a name="table05450516616"></a><table cellpadding="4" cellspacing="0" summary="" id="EN-US_TOPIC_0000001764491796__table05450516616" frame="border" border="1" rules="all"><caption><b>Table 1 </b>Maximum number of calculated distinct values determined by hll_default_log2m and hll_default_regwidth</caption><thead align="left"><tr id="EN-US_TOPIC_0000001764491796__row8546651063"><th align="left" class="cellrowborder" valign="top" width="16.666666666666664%" id="mcps1.3.43.6.2.7.1.1"><p id="EN-US_TOPIC_0000001764491796__p254617515615">log2m</p>
</th>
<th align="left" class="cellrowborder" valign="top" width="16.666666666666664%" id="mcps1.3.43.6.2.7.1.2"><p id="EN-US_TOPIC_0000001764491796__p19546551964">regwidth = 1</p>
</th>
<th align="left" class="cellrowborder" valign="top" width="16.666666666666664%" id="mcps1.3.43.6.2.7.1.3"><p id="EN-US_TOPIC_0000001764491796__p1554655763">regwidth = 2</p>
</th>
<th align="left" class="cellrowborder" valign="top" width="16.666666666666664%" id="mcps1.3.43.6.2.7.1.4"><p id="EN-US_TOPIC_0000001764491796__p195461551168">regwidth = 3</p>
</th>
<th align="left" class="cellrowborder" valign="top" width="16.666666666666664%" id="mcps1.3.43.6.2.7.1.5"><p id="EN-US_TOPIC_0000001764491796__p19546175262">regwidth = 4</p>
</th>
<th align="left" class="cellrowborder" valign="top" width="16.666666666666664%" id="mcps1.3.43.6.2.7.1.6"><p id="EN-US_TOPIC_0000001764491796__p554635064">regwidth = 5</p>
</th>
</tr>
</thead>
<tbody><tr id="EN-US_TOPIC_0000001764491796__row7546145068"><td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.1 "><p id="EN-US_TOPIC_0000001764491796__p65465511610">10</p>
</td>
<td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.2 "><p id="EN-US_TOPIC_0000001764491796__p165462051966">7.4e+02</p>
</td>
<td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.3 "><p id="EN-US_TOPIC_0000001764491796__p35471751267">3.0e+03</p>
</td>
<td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.4 "><p id="EN-US_TOPIC_0000001764491796__p13547751362">4.7e+04</p>
</td>
<td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.5 "><p id="EN-US_TOPIC_0000001764491796__p254716513614">1.2e+07</p>
</td>
<td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.6 "><p id="EN-US_TOPIC_0000001764491796__p2547051965">7.9e+11</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001764491796__row2054725162"><td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.1 "><p id="EN-US_TOPIC_0000001764491796__p754716511612">11</p>
</td>
<td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.2 "><p id="EN-US_TOPIC_0000001764491796__p205478510615">1.5e+03</p>
</td>
<td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.3 "><p id="EN-US_TOPIC_0000001764491796__p19547155568">5.9e+03</p>
</td>
<td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.4 "><p id="EN-US_TOPIC_0000001764491796__p135478510611">9.5e+04</p>
</td>
<td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.5 "><p id="EN-US_TOPIC_0000001764491796__p2547185267">2.4e+07</p>
</td>
<td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.6 "><p id="EN-US_TOPIC_0000001764491796__p45471752614">1.6e+12</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001764491796__row205471751465"><td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.1 "><p id="EN-US_TOPIC_0000001764491796__p175471951463">12</p>
</td>
<td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.2 "><p id="EN-US_TOPIC_0000001764491796__p554725762">3.0e+03</p>
</td>
<td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.3 "><p id="EN-US_TOPIC_0000001764491796__p14547125266">1.2e+04</p>
</td>
<td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.4 "><p id="EN-US_TOPIC_0000001764491796__p18547175868">1.9e+05</p>
</td>
<td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.5 "><p id="EN-US_TOPIC_0000001764491796__p2547951364">4.8e+07</p>
</td>
<td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.6 "><p id="EN-US_TOPIC_0000001764491796__p135491151568">3.2e+12</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001764491796__row0549185863"><td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.1 "><p id="EN-US_TOPIC_0000001764491796__p95491259619">13</p>
</td>
<td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.2 "><p id="EN-US_TOPIC_0000001764491796__p1918182817811">5.9e+03</p>
</td>
<td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.3 "><p id="EN-US_TOPIC_0000001764491796__p15549145567">2.4e+04</p>
</td>
<td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.4 "><p id="EN-US_TOPIC_0000001764491796__p75491351467">3.8e+05</p>
</td>
<td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.5 "><p id="EN-US_TOPIC_0000001764491796__p10549158615">9.7e+07</p>
</td>
<td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.6 "><p id="EN-US_TOPIC_0000001764491796__p155491955618">6.3e+12</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001764491796__row3549135769"><td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.1 "><p id="EN-US_TOPIC_0000001764491796__p154905165">14</p>
</td>
<td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.2 "><p id="EN-US_TOPIC_0000001764491796__p6549195767">1.2e+04</p>
</td>
<td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.3 "><p id="EN-US_TOPIC_0000001764491796__p135491951617">4.7e+04</p>
</td>
<td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.4 "><p id="EN-US_TOPIC_0000001764491796__p15491951765">7.6e+05</p>
</td>
<td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.5 "><p id="EN-US_TOPIC_0000001764491796__p0549555619">1.9e+08</p>
</td>
<td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.6 "><p id="EN-US_TOPIC_0000001764491796__p75490513614">1.3e+13</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001764491796__row45491151168"><td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.1 "><p id="EN-US_TOPIC_0000001764491796__p8549195663">15</p>
</td>
<td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.2 "><p id="EN-US_TOPIC_0000001764491796__p4549351065">2.4e+04</p>
</td>
<td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.3 "><p id="EN-US_TOPIC_0000001764491796__p105491358611">9.5e+04</p>
</td>
<td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.4 "><p id="EN-US_TOPIC_0000001764491796__p14549851461">1.5e+06</p>
</td>
<td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.5 "><p id="EN-US_TOPIC_0000001764491796__p135496512615">3.9e+08</p>
</td>
<td class="cellrowborder" valign="top" width="16.666666666666664%" headers="mcps1.3.43.6.2.7.1.6 "><p id="EN-US_TOPIC_0000001764491796__p254917520612">2.5e+13</p>
</td>
</tr>
</tbody>
</table>
</div>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section1785343972518"><h4 class="sectiontitle">hll_default_expthresh</h4><p id="EN-US_TOPIC_0000001764491796__p282873734212"><strong id="EN-US_TOPIC_0000001764491796__b1471694442911">Parameter description</strong>: Specifies the default threshold for switching from the <strong id="EN-US_TOPIC_0000001764491796__b167210315541">explicit</strong> mode to the <strong id="EN-US_TOPIC_0000001764491796__b785113104540">sparse</strong> mode.</p>
<p id="EN-US_TOPIC_0000001764491796__p134807160159"><strong id="EN-US_TOPIC_0000001764491796__b16143163734813">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p442552213427"><strong id="EN-US_TOPIC_0000001764491796__b182371413121814">Value range</strong>: an integer ranging from –1 to 7 <strong id="EN-US_TOPIC_0000001764491796__b5347336204">–1</strong> indicates the auto mode; <strong id="EN-US_TOPIC_0000001764491796__b1135173362018">0</strong> indicates that the <strong id="EN-US_TOPIC_0000001764491796__b635133162014">explicit</strong> mode is skipped; a value from 1 to 7 indicates that the mode is switched when the number of distinct values reaches 2<sup id="EN-US_TOPIC_0000001764491796__sup1236203332011">hll_default_expthresh</sup>.</p>
<p id="EN-US_TOPIC_0000001764491796__p185313942518"><strong id="EN-US_TOPIC_0000001764491796__b1254752973419">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b6548162917346">–1</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section95372411258"><h4 class="sectiontitle">hll_default_sparseon</h4><p id="EN-US_TOPIC_0000001764491796__p753754142515"><strong id="EN-US_TOPIC_0000001764491796__b7640152103514">Parameter description</strong>: Specifies whether to enable the <strong id="EN-US_TOPIC_0000001764491796__b1712145655418">sparse</strong> mode by default.</p>
<p id="EN-US_TOPIC_0000001764491796__p6398647144219"><strong id="EN-US_TOPIC_0000001764491796__b179881839134814">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p17537104112252"><strong id="EN-US_TOPIC_0000001764491796__b66499804">Valid value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b842352706111635">0</strong> and <strong id="EN-US_TOPIC_0000001764491796__b842352706111638">1</strong> <strong id="EN-US_TOPIC_0000001764491796__b62861124103811">0</strong> indicates that the <strong id="EN-US_TOPIC_0000001764491796__b942111106556">sparse</strong> mode is disabled by default. <strong id="EN-US_TOPIC_0000001764491796__b13632018104017">1</strong> indicates that the <strong id="EN-US_TOPIC_0000001764491796__b1072152517552">sparse</strong> mode is enabled by default.</p>
<p id="EN-US_TOPIC_0000001764491796__p7537164112252"><strong id="EN-US_TOPIC_0000001764491796__b934831913594">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b123488198597">1</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section13489114392513"><h4 class="sectiontitle">hll_max_sparse</h4><p id="EN-US_TOPIC_0000001764491796__p134893434251"><strong id="EN-US_TOPIC_0000001764491796__b10914103519400">Parameter description</strong>: Specifies the size of <strong id="EN-US_TOPIC_0000001764491796__b1128613524407">max_sparse</strong>.</p>
<p id="EN-US_TOPIC_0000001764491796__p954735813422"><strong id="EN-US_TOPIC_0000001764491796__b15518104312489">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p164891843112515"><strong id="EN-US_TOPIC_0000001764491796__b35751844115915">Value range</strong>: an integer ranging from –1 to <strong id="EN-US_TOPIC_0000001764491796__b14215253715">INT_MAX</strong></p>
<p id="EN-US_TOPIC_0000001764491796__p848917437259"><strong id="EN-US_TOPIC_0000001764491796__b172868129410">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b8287141211412">–1</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section10636183653718"><h4 class="sectiontitle">enable_compress_hll</h4><p id="EN-US_TOPIC_0000001764491796__p16367361374"><strong id="EN-US_TOPIC_0000001764491796__b143909487910">Parameter description</strong>: Specifies whether to enable memory optimization for HLL.</p>
<p id="EN-US_TOPIC_0000001764491796__p1654718610431"><strong id="EN-US_TOPIC_0000001764491796__b11710943194815">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p18474219104112"><strong id="EN-US_TOPIC_0000001764491796__b58854511693">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__ul5475919104111"><li id="EN-US_TOPIC_0000001764491796__li13475219104117"><strong id="EN-US_TOPIC_0000001764491796__b156051919234">on</strong> or <strong id="EN-US_TOPIC_0000001764491796__b1332226122318">true</strong> indicates that memory optimization is enabled.</li><li id="EN-US_TOPIC_0000001764491796__li134756199419"><strong id="EN-US_TOPIC_0000001764491796__b17840165217235">off</strong> or <strong id="EN-US_TOPIC_0000001764491796__b340013591231">false</strong> indicates that memory optimization is disabled.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__p15636193614372"><strong id="EN-US_TOPIC_0000001764491796__b157910562911">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b157921256496">off</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section1692311470471"><h4 class="sectiontitle">approx_count_distinct_precision</h4><p id="EN-US_TOPIC_0000001764491796__p1194119487477"><strong id="EN-US_TOPIC_0000001764491796__b144307221519">Parameter description</strong>: Specifies the number of buckets in the HyperLogLog++ (HLL++) algorithm. This parameter can be used to adjust the error rate of the <strong id="EN-US_TOPIC_0000001764491796__b17289942533">approx_count_distinct </strong>aggregate function. The number of buckets affects the precision of estimating the distinct value. Having more buckets increases the accuracy of the estimation. The deviation range is as follows: [–1.04/2<sup id="EN-US_TOPIC_0000001764491796__sup1095651887">log2m*1/2</sup>, +1.04/2<sup id="EN-US_TOPIC_0000001764491796__sup119701805">log2m*1/2</sup>]</p>
<p id="EN-US_TOPIC_0000001764491796__p1794112489478"><strong id="EN-US_TOPIC_0000001764491796__b753163336">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p7941124810474"><strong id="EN-US_TOPIC_0000001764491796__b19645433054">Value range</strong>: an integer ranging from 10 to 20.</p>
<p id="EN-US_TOPIC_0000001764491796__p7941164864713"><strong id="EN-US_TOPIC_0000001764491796__b29341217263">Default value</strong>: 17</p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section1765913299426"><a name="EN-US_TOPIC_0000001764491796__section1765913299426"></a><a name="section1765913299426"></a><h4 class="sectiontitle">udf_memory_limit</h4><p id="EN-US_TOPIC_0000001764491796__p106541811908"><strong id="EN-US_TOPIC_0000001764491796__b2330163113915">Parameter description</strong>: Controls the maximum physical memory that can be used when each CN or DN executes UDFs.</p>
<p id="EN-US_TOPIC_0000001764491796__p496143171915"><strong id="EN-US_TOPIC_0000001764491796__b16223194415481">Type</strong>: POSTMASTER</p>
<p id="EN-US_TOPIC_0000001764491796__p186572111104"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0085033176_en-us_topic_0059778686_a8791c882938f4e6c9ae407641e405449">Value range</strong>: an integer ranging from 200 x 1024 to the value of <a href="dws_04_0893.html#EN-US_TOPIC_0000001811610373__sadc1e0e8c1c246a4a6cad3967deebaad">max_process_memory</a> and the unit is KB.</p>
<p id="EN-US_TOPIC_0000001764491796__p16611811506"><strong id="EN-US_TOPIC_0000001764491796__b12816154581716">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b781710457171">0.05 * max_process_memory</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section0948171616421"><h4 class="sectiontitle">FencedUDFMemoryLimit</h4><p id="EN-US_TOPIC_0000001764491796__p12890171344316"><strong id="EN-US_TOPIC_0000001764491796__b842352706182822">Parameter description</strong>: Controls the virtual memory used by each fenced udf worker process.</p>
<p id="EN-US_TOPIC_0000001764491796__p1131121704311"><strong id="EN-US_TOPIC_0000001764491796__b24084465489">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p125399121402"><strong id="EN-US_TOPIC_0000001764491796__b578119269104">Suggestion</strong>: You are not advised to set this parameter. You can set <a href="#EN-US_TOPIC_0000001764491796__section1765913299426">udf_memory_limit</a> instead. </p>
<p id="EN-US_TOPIC_0000001764491796__p69576180448"><strong id="EN-US_TOPIC_0000001764491796__b842352706182917">Value range</strong>: an integer. The unit can be KB, MB, or GB. <strong id="EN-US_TOPIC_0000001764491796__b1901530193619">0</strong> indicates that the memory is not limited.</p>
<p id="EN-US_TOPIC_0000001764491796__p5155164174613"><strong id="EN-US_TOPIC_0000001764491796__b227128804">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b279437292">0</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section4605202011486"><h4 class="sectiontitle">enable_pbe_optimization</h4><p id="EN-US_TOPIC_0000001764491796__p1162116209481"><strong id="EN-US_TOPIC_0000001764491796__b453379124317">Parameter description</strong>: Specifies whether the optimizer optimizes the query plan for statements executed in Parse Bind Execute (PBE) mode.</p>
<p id="EN-US_TOPIC_0000001764491796__p1570952701717"><strong id="EN-US_TOPIC_0000001764491796__b0942828593">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p166018201483"><strong id="EN-US_TOPIC_0000001764491796__b9542154112440">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__ul144954452277"><li id="EN-US_TOPIC_0000001764491796__li8500154512712"><strong id="EN-US_TOPIC_0000001764491796__b13354135164412">on</strong> indicates that the optimizer optimizes the query plan.</li><li id="EN-US_TOPIC_0000001764491796__li11512114512718"><strong id="EN-US_TOPIC_0000001764491796__b226014273450">off</strong> indicates that the optimization does not optimize the query plan.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__p19673182074819"><strong id="EN-US_TOPIC_0000001764491796__b964325026">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b242590174">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section46891552174813"><h4 class="sectiontitle">enable_light_proxy</h4><p id="EN-US_TOPIC_0000001764491796__p13702145274818"><strong id="EN-US_TOPIC_0000001764491796__b11250175084515">Parameter description</strong>: Specifies whether the optimizer optimizes the execution of simple queries on CNs.</p>
<p id="EN-US_TOPIC_0000001764491796__p469693512176"><strong id="EN-US_TOPIC_0000001764491796__b57321436591">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p5740195212482"><strong id="EN-US_TOPIC_0000001764491796__b1789111246463">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__ul10758752154819"><li id="EN-US_TOPIC_0000001764491796__li12763105244816"><strong id="EN-US_TOPIC_0000001764491796__b4265203074615">on</strong> indicates that the optimizer optimizes the execution.</li><li id="EN-US_TOPIC_0000001764491796__li207798528488"><strong id="EN-US_TOPIC_0000001764491796__b8422193515464">off</strong> indicates that the optimization does not optimize the execution.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__p7791152114813"><strong id="EN-US_TOPIC_0000001764491796__b533384614612">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b13332465465">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section11251245438"><h4 class="sectiontitle">enable_parallel_ddl</h4><p id="EN-US_TOPIC_0000001764491796__p186209614439"><strong id="EN-US_TOPIC_0000001764491796__b810103618116">Parameter description</strong>: Controls whether multiple CNs can concurrently perform DDL operations on the same database object.</p>
<p id="EN-US_TOPIC_0000001764491796__p104563513431"><strong id="EN-US_TOPIC_0000001764491796__b1468514814483">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p146306604316"><strong id="EN-US_TOPIC_0000001764491796__b97964976">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__ul1984619152455"><li id="EN-US_TOPIC_0000001764491796__li3848171554517"><strong id="EN-US_TOPIC_0000001764491796__b1156812482113">on</strong> indicates that DDL operations can be performed safely and that no distributed deadlock occurs.</li><li id="EN-US_TOPIC_0000001764491796__li48518155454"><strong id="EN-US_TOPIC_0000001764491796__b203511789126">off</strong> indicates that DDL operations cannot be performed safely and that distributed deadlocks may occur.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__p1363476194311"><strong id="EN-US_TOPIC_0000001764491796__b1964583257">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b238237107">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section862650171317"><h4 class="sectiontitle">gc_fdw_verify_option</h4><p id="EN-US_TOPIC_0000001764491796__p1962712061319"><strong id="EN-US_TOPIC_0000001764491796__b536541819212">Parameter description</strong>: Specifies whether to enable the logic for verifying the number of rows in a result set in the collaborative analysis. This parameter is supported only by clusters of version 8.1.3.310 or later.</p>
<p id="EN-US_TOPIC_0000001764491796__p15627110101320"><strong id="EN-US_TOPIC_0000001764491796__b1645956149">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p11627403136"><strong id="EN-US_TOPIC_0000001764491796__b1438575400">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__ul106273010136"><li id="EN-US_TOPIC_0000001764491796__li17627207130"><strong id="EN-US_TOPIC_0000001764491796__b745120442117">on</strong> indicates that the logic for verifying the number of rows in the result set is enabled. The <strong id="EN-US_TOPIC_0000001764491796__b145154410120">SELECT COUNT</strong> statement is used to obtain the expected number of rows and compare it with the actual number of rows.</li><li id="EN-US_TOPIC_0000001764491796__li106276011318"><strong id="EN-US_TOPIC_0000001764491796__b4559726210204">off</strong> indicates that the logic for verifying the number of rows in the result set is disabled and only the required result set is obtained.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__p14627180151313"><strong id="EN-US_TOPIC_0000001764491796__b1622893394">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b436425208">on</strong></p>
<div class="note" id="EN-US_TOPIC_0000001764491796__note17148125103713"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><ul id="EN-US_TOPIC_0000001764491796__ul202871820133520"><li id="EN-US_TOPIC_0000001764491796__li1728716208357">If this parameter is enabled, the performance deteriorates slightly. In performance-sensitive scenarios, you can disable this parameter to improve the performance.</li><li id="EN-US_TOPIC_0000001764491796__li1428152213353">If the result set row count check fails, an exception will be reported. To enable cooperative analysis logs, set <strong id="EN-US_TOPIC_0000001764491796__b195216447237">log_min_messages</strong> to <strong id="EN-US_TOPIC_0000001764491796__b81641951182312">debug1</strong> and <strong id="EN-US_TOPIC_0000001764491796__b161116567239">logging_module</strong> to <strong id="EN-US_TOPIC_0000001764491796__b7993101242410">'on(COOP_ANALYZE)'</strong>.</li></ul>
</div></div>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section29017124241"><h4 class="sectiontitle">show_acce_estimate_detail</h4><p id="EN-US_TOPIC_0000001764491796__p119811252420"><strong id="EN-US_TOPIC_0000001764491796__b39830174137">Parameter description</strong>: When the <span id="EN-US_TOPIC_0000001764491796__text199466072">GaussDB(DWS)</span> cluster is accelerated (<a href="dws_04_0945.html#EN-US_TOPIC_0000001811490665__section13787157164412">acceleration_with_compute_pool</a> is set to <strong id="EN-US_TOPIC_0000001764491796__b111314815134">on</strong>), specifies whether the <strong id="EN-US_TOPIC_0000001764491796__b1593711104144">EXPLAIN</strong> statement displays the evaluation information about execution plan pushdown to computing Node Groups. The evaluation information is generally used by O&amp;M personnel during maintenance, and it may affect the output display of the <strong id="EN-US_TOPIC_0000001764491796__b872662111611">EXPLAIN</strong> statement. Therefore, this parameter is disabled by default. The evaluation information is displayed only if the <strong id="EN-US_TOPIC_0000001764491796__b156850412165">verbose</strong> option of the <strong id="EN-US_TOPIC_0000001764491796__b6881646191612">EXPLAIN</strong> statement is enabled.</p>
<p id="EN-US_TOPIC_0000001764491796__p39415541438"><strong id="EN-US_TOPIC_0000001764491796__b1822194994810">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p710810127247"><strong id="EN-US_TOPIC_0000001764491796__b1289084112710">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__ul1411511214248"><li id="EN-US_TOPIC_0000001764491796__li91171112172414"><strong id="EN-US_TOPIC_0000001764491796__b86081331192418">on</strong> indicates that the evaluation information is displayed in the output of the <strong id="EN-US_TOPIC_0000001764491796__b9422184052412">EXPLAIN</strong> statement.</li><li id="EN-US_TOPIC_0000001764491796__li91221212192418"><strong id="EN-US_TOPIC_0000001764491796__b11231122112404">off</strong> indicates that the evaluation information is not displayed in the output of the <strong id="EN-US_TOPIC_0000001764491796__b12321921124019">EXPLAIN</strong> statement.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__p512641262419"><strong id="EN-US_TOPIC_0000001764491796__en-us_topic_0059778871_en-us_topic_0058967732_b46080773_10">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b842352706145110">off</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section8513287116"><a name="EN-US_TOPIC_0000001764491796__section8513287116"></a><a name="section8513287116"></a><h4 class="sectiontitle">full_group_by_mode</h4><p id="EN-US_TOPIC_0000001764491796__p13858122818117"><strong id="EN-US_TOPIC_0000001764491796__b5105171518243">Parameter description</strong>: Used in conjunction with <strong id="EN-US_TOPIC_0000001764491796__b692212322514">disable_full_group_by_mysql</strong> in <a href="dws_04_0931.html#EN-US_TOPIC_0000001811490801__section1980124735516">behavior_compat_options</a> to control two different behaviors when <strong id="EN-US_TOPIC_0000001764491796__b645454482513">disable_full_group_by_mysql syntax</strong> is enabled.</p>
<p id="EN-US_TOPIC_0000001764491796__p18581280113"><strong id="EN-US_TOPIC_0000001764491796__b1229876944">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p178581028201112"><strong id="EN-US_TOPIC_0000001764491796__b1350896122">Value range</strong>: a string</p>
<ul id="EN-US_TOPIC_0000001764491796__ul12858112812117"><li id="EN-US_TOPIC_0000001764491796__li11859628171110"><strong id="EN-US_TOPIC_0000001764491796__b61231639274">nullpadding</strong> indicates that NULL values in non-aggregate columns are filled with the non-NULL values in that column, potentially resulting in different rows in the result set.</li><li id="EN-US_TOPIC_0000001764491796__li1985952815113"><strong id="EN-US_TOPIC_0000001764491796__b4221528172715">notpadding</strong> indicates that NULL values in non-aggregate columns are not processed, and the entire row data is used, resulting in a random row for non-aggregate columns in the result set.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__p108596286118"><strong id="EN-US_TOPIC_0000001764491796__b1840742102715">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b4841184282712">notpadding</strong></p>
<div class="notice" id="EN-US_TOPIC_0000001764491796__note195831424201713"><span class="noticetitle"><img src="public_sys-resources/notice_3.0-en-us.png"> </span><div class="noticebody"><p id="EN-US_TOPIC_0000001764491796__p1258342413172">This parameter only takes effect when <strong id="EN-US_TOPIC_0000001764491796__b1335615262281">disable_full_group_by_mysql</strong> is enabled in the MySQL-compatible library and non-aggregate columns are present in the query. The two behaviors of this parameter only apply to non-aggregate columns in the query.</p>
</div></div>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section11675179153316"><h4 class="sectiontitle">enable_cudesc_streaming</h4><p id="EN-US_TOPIC_0000001764491796__p1843962982613"><strong id="EN-US_TOPIC_0000001764491796__b6547194911396">Parameter description</strong>: Specifies whether to use the cudesc streaming path for accessing data across logical clusters in the decoupled storage and compute architecture. This parameter is supported only by clusters of version 9.1.0 or later.</p>
<p id="EN-US_TOPIC_0000001764491796__p5439829142614"><strong id="EN-US_TOPIC_0000001764491796__b656327254">Type</strong>: SUSET</p>
<div class="p" id="EN-US_TOPIC_0000001764491796__p3133104415319"><strong id="EN-US_TOPIC_0000001764491796__b52026867684846">Value range</strong>: enumerated values<ul id="EN-US_TOPIC_0000001764491796__ul1251173295314"><li id="EN-US_TOPIC_0000001764491796__li2251123211530"><strong id="EN-US_TOPIC_0000001764491796__b1113751044110">off</strong> indicates that cudesc streaming is disabled.</li><li id="EN-US_TOPIC_0000001764491796__li125183255310"><strong id="EN-US_TOPIC_0000001764491796__b39822524117">on</strong> indicates that cudesc streaming is enabled.</li><li id="EN-US_TOPIC_0000001764491796__li3251173265319"><strong id="EN-US_TOPIC_0000001764491796__b129821830104112">only_read_on</strong> indicates that cudesc streaming is supported only during data reading.</li></ul>
</div>
<p id="EN-US_TOPIC_0000001764491796__p84391291263"><strong id="EN-US_TOPIC_0000001764491796__b1947954034117">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b1479240134115">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section4947124475920"><h4 class="sectiontitle">force_read_from_rw</h4><p id="EN-US_TOPIC_0000001764491796__p18169103852514"><strong id="EN-US_TOPIC_0000001764491796__b161691638122517">Parameter description</strong>: Forces data to be read from other logical clusters in the decoupled storage and compute architecture (i.e., read data from the logical cluster where the table resides). This parameter is supported only by clusters of version 9.0.0 or later.</p>
<p id="EN-US_TOPIC_0000001764491796__p3169133822512"><strong id="EN-US_TOPIC_0000001764491796__b739600830">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p11701138172515"><strong id="EN-US_TOPIC_0000001764491796__b826235165">Value range</strong>: Boolean</p>
<p id="EN-US_TOPIC_0000001764491796__p9170638112511"><strong id="EN-US_TOPIC_0000001764491796__b1050984904">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b74616056">off</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section273355961016"><h4 class="sectiontitle">kv_sync_up_timeout</h4><p id="EN-US_TOPIC_0000001764491796__p3248238474"><strong id="EN-US_TOPIC_0000001764491796__b8229192111264">Parameter description</strong>: Specifies the timeout interval for KV synchronization in the decoupled storage and compute architecture. This parameter is supported only by clusters of version 9.0.0 or later.</p>
<p id="EN-US_TOPIC_0000001764491796__p422912172619"><strong id="EN-US_TOPIC_0000001764491796__b175574490">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p1229192119263"><strong id="EN-US_TOPIC_0000001764491796__b10229192116265">Value range</strong>: an integer ranging from 0 to 2147483647</p>
<p id="EN-US_TOPIC_0000001764491796__p82291021122613"><strong id="EN-US_TOPIC_0000001764491796__b104821005536">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b5483100115319">10min</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section12654358145219"><h4 class="sectiontitle">enable_insert_foreign_table_dop</h4><p id="EN-US_TOPIC_0000001764491796__p18654125810526"><strong id="EN-US_TOPIC_0000001764491796__b26545587524">Parameter description</strong>: Specifies whether to enable DOP acceleration when data is written into an OBS foreign table. The number of DOP threads on each DN is determined by <strong id="EN-US_TOPIC_0000001764491796__b910761314529">query_dop</strong>. By adjusting its value, you can control the level of parallelism for your queries. This parameter is supported only in 9.1.0.200 and later versions.</p>
<p id="EN-US_TOPIC_0000001764491796__p17654158115219"><strong id="EN-US_TOPIC_0000001764491796__b278865231">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p5588105615546"><strong id="EN-US_TOPIC_0000001764491796__b1229801231">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__ul85881356145411"><li id="EN-US_TOPIC_0000001764491796__li135882056155414"><strong id="EN-US_TOPIC_0000001764491796__b14244133845213">on</strong> indicates that foreign table DOP acceleration is enabled.</li><li id="EN-US_TOPIC_0000001764491796__li5588756145420"><strong id="EN-US_TOPIC_0000001764491796__b085464414526">off</strong> indicates that foreign table DOP acceleration is disabled.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__p165518586520"><strong id="EN-US_TOPIC_0000001764491796__b293172624">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b2116162404">off</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section1438811248569"><h4 class="sectiontitle">enable_insert_foreign_table_dop_opt</h4><p id="EN-US_TOPIC_0000001764491796__p83882249561"><strong id="EN-US_TOPIC_0000001764491796__b19388152415569">Parameter description</strong>: Specifies whether to enable partition redistribution optimization after <strong id="EN-US_TOPIC_0000001764491796__b066415965219">insert dop</strong> is enabled for a foreign table. If the number of partitions to be exported is greater than 10 times the number of partitions, you are advised to enable this function to reduce small files in a single partition and improve export performance. This parameter is supported only in 9.1.0.200 and later versions.</p>
<p id="EN-US_TOPIC_0000001764491796__p638819245566"><strong id="EN-US_TOPIC_0000001764491796__b658513071">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p13389102435618"><strong id="EN-US_TOPIC_0000001764491796__b1740906672">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__ul73893244563"><li id="EN-US_TOPIC_0000001764491796__li338932410562"><strong id="EN-US_TOPIC_0000001764491796__b947723518534">on</strong> indicates that the <strong id="EN-US_TOPIC_0000001764491796__b1236754265318">insert dop</strong> redistribution optimization of the partitioned foreign table is enabled.</li><li id="EN-US_TOPIC_0000001764491796__li1138917247561"><strong id="EN-US_TOPIC_0000001764491796__b16556175215317">off</strong> indicates that the insert dop redistribution optimization of the partitioned foreign table is disabled.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__p2038972495620"><strong id="EN-US_TOPIC_0000001764491796__b816147972">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b913537831">off</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section19418514112914"><a name="EN-US_TOPIC_0000001764491796__section19418514112914"></a><a name="section19418514112914"></a><h4 class="sectiontitle">enable_hstore_binlog_table</h4><p id="EN-US_TOPIC_0000001764491796__p13103982319"><strong id="EN-US_TOPIC_0000001764491796__b310314817316">Parameter description</strong>: Specifies whether binlog tables can be created.</p>
<p id="EN-US_TOPIC_0000001764491796__p1710314818313"><strong id="EN-US_TOPIC_0000001764491796__b1193183986">Type</strong>: SIGHUP</p>
<p id="EN-US_TOPIC_0000001764491796__p110319814311"><strong id="EN-US_TOPIC_0000001764491796__b1469417019">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__ul11031483318"><li id="EN-US_TOPIC_0000001764491796__li1610378143116"><strong id="EN-US_TOPIC_0000001764491796__b1431545737596">on</strong> indicates that binlog tables can be created.</li><li id="EN-US_TOPIC_0000001764491796__li81039893118"><strong id="EN-US_TOPIC_0000001764491796__b1927173322815">off</strong> indicates that binlog tables cannot be created.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__p010318816315"><strong id="EN-US_TOPIC_0000001764491796__b1279701261">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b1117083424">off</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section192371051875"><a name="EN-US_TOPIC_0000001764491796__section192371051875"></a><a name="section192371051875"></a><h4 class="sectiontitle">enable_generate_binlog</h4><p id="EN-US_TOPIC_0000001764491796__p523775674"><strong id="EN-US_TOPIC_0000001764491796__b189361145193110">Parameter description</strong>: Specifies whether binlogs are generated for DML operations on binlog tables in the current session. This parameter is supported only by clusters of version 9.1.0.200 or later.</p>
<p id="EN-US_TOPIC_0000001764491796__p9237554716"><strong id="EN-US_TOPIC_0000001764491796__b1608398203">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001764491796__p8237951475"><strong id="EN-US_TOPIC_0000001764491796__b63746308">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001764491796__ul1523816511714"><li id="EN-US_TOPIC_0000001764491796__li18238165171"><strong id="EN-US_TOPIC_0000001764491796__b13855183711">on</strong> indicates that binlogs are generated.</li><li id="EN-US_TOPIC_0000001764491796__li1323835374"><strong id="EN-US_TOPIC_0000001764491796__b567715811371">off</strong> indicates that binlogs are not generated.</li></ul>
<p id="EN-US_TOPIC_0000001764491796__p19238556715"><strong id="EN-US_TOPIC_0000001764491796__b2103165672">Default value</strong>: <strong id="EN-US_TOPIC_0000001764491796__b1300993374">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764491796__section632013281225"><h4 class="sectiontitle">binlog_consume_timeout</h4><p id="EN-US_TOPIC_0000001764491796__p478093010221"><strong id="EN-US_TOPIC_0000001764491796__b2106516123712">Parameter description</strong>: Specifies the duration for cyclically determining whether all binlog records are consumed during binlog table scaling or <strong id="EN-US_TOPIC_0000001764491796__b880292817395">VACUUM FULL</strong> operations. This parameter is supported only by 8.3.0.100 and later versions. The unit is second.</p>
<p id="EN-US_TOPIC_0000001764491796__p1778073013225"><strong id="EN-US_TOPIC_0000001764491796__b1290008733">Type</strong>: SIGHUP</p>
<p id="EN-US_TOPIC_0000001764491796__p1478083017227"><strong id="EN-US_TOPIC_0000001764491796__b07064614408">Value range</strong>: an integer ranging from 0 to 86400</p>
<p id="EN-US_TOPIC_0000001764491796__p97802302223"><strong id="EN-US_TOPIC_0000001764491796__b2741155132319">Default value</strong>: 3600</p>
</div>
</div>
<div>
<div class="familylinks">
<div class="parentlink"><strong>Parent topic:</strong> <a href="dws_04_0883.html">GUC Parameters of the GaussDB(DWS) Database</a></div>
</div>
</div>
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