doc-exports/docs/dws/dev/dws_04_0909.html

<a name="EN-US_TOPIC_0000001510522673"></a><a name="EN-US_TOPIC_0000001510522673"></a>

<h1 class="topictitle1">Optimizer Method Configuration</h1>
<div id="body8662426"><p id="EN-US_TOPIC_0000001510522673__en-us_topic_0059778346_p318945515">These configuration parameters provide a crude method of influencing the query plans chosen by the query optimizer. If the default plan chosen by the optimizer for a particular query is not optimal, a temporary solution is to use one of these configuration parameters to force the optimizer to choose a different plan. Better ways include adjusting the optimizer cost constants, manually running <strong id="EN-US_TOPIC_0000001510522673__b91137528207">ANALYZE</strong>, increasing the value of the <a href="dws_04_0912.html#EN-US_TOPIC_0000001460562696__sa5c1527051e54fbdb6c5346d54bcbf5a">default_statistics_target</a> configuration parameter, and adding the statistics collected in a specific column using <strong id="EN-US_TOPIC_0000001510522673__b61131852152018">ALTER TABLE SET STATISTICS</strong>.</p>
<div class="section" id="EN-US_TOPIC_0000001510522673__s61c2f3870a4a45b7b92e186c4e6037a7"><h4 class="sectiontitle">enable_bitmapscan</h4><p id="EN-US_TOPIC_0000001510522673__a2075cc5e286649bfb8421648b506b3f7"><strong id="EN-US_TOPIC_0000001510522673__b1061519514172">Parameter description</strong>: Controls whether the query optimizer uses the bitmap-scan plan type.</p>
<p id="EN-US_TOPIC_0000001510522673__p624153517198"><strong id="EN-US_TOPIC_0000001510522673__b89211962125">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__a96e3a2acc5ea411080df76a1b1e13fe3"><strong id="EN-US_TOPIC_0000001510522673__b1872913092114">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001510522673__ubdaa96b4e18a4122ad56efc974500c1a"><li id="EN-US_TOPIC_0000001510522673__l26dbbe6b618449dc823a68f6546c567b"><strong id="EN-US_TOPIC_0000001510522673__b118862122111">on</strong> indicates it is enabled.</li><li id="EN-US_TOPIC_0000001510522673__l4eaa87836bf24c61942700028e5fcf71"><strong id="EN-US_TOPIC_0000001510522673__b18928319210">off</strong> indicates it is disabled.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__a0014e3426a374260a91ffef1b9e1689a"><strong id="EN-US_TOPIC_0000001510522673__b14457111617210">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b5462216152118">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__s8d922e5a221548c2b399032bce2cc840"><h4 class="sectiontitle">enable_hashagg</h4><p id="EN-US_TOPIC_0000001510522673__aec9fcdb6b2b4410b899d49ed9a03b64e"><strong id="EN-US_TOPIC_0000001510522673__b17519532132019">Parameter description</strong>: Controls whether the query optimizer uses the Hash aggregation plan type.</p>
<p id="EN-US_TOPIC_0000001510522673__p8293115416253"><strong id="EN-US_TOPIC_0000001510522673__b66161778128">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__a0d0c94e9e01a435b94ad76e19dec9ffc"><strong id="EN-US_TOPIC_0000001510522673__b1150081715213">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001510522673__u43706081ab2347bcb2d8e119ae6adfc8"><li id="EN-US_TOPIC_0000001510522673__ld08ba9ef862c4ed9b44ab0479996b169"><strong id="EN-US_TOPIC_0000001510522673__b145881184217">on</strong> indicates it is enabled.</li><li id="EN-US_TOPIC_0000001510522673__la2f40fe78142412ca7474f8b6365b5f7"><strong id="EN-US_TOPIC_0000001510522673__b148801119202114">off</strong> indicates it is disabled.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__a3866647b152a40a68af7c53f37d0fb57"><strong id="EN-US_TOPIC_0000001510522673__b1125617623">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b1183402355">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__section16127427102819"><h4 class="sectiontitle">enable_mixedagg</h4><p id="EN-US_TOPIC_0000001510522673__p3667114318187"><strong id="EN-US_TOPIC_0000001510522673__b12459827542518">Parameter description</strong>: Controls whether the query optimizer uses the Mixed Agg plan type. (This parameter is supported by version 8.2.0 or later clusters.)</p>
<p id="EN-US_TOPIC_0000001510522673__p101271227192819"><strong id="EN-US_TOPIC_0000001510522673__b1334077621">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__p4127182710281"><strong id="EN-US_TOPIC_0000001510522673__b437741726">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001510522673__ul1912712277287"><li id="EN-US_TOPIC_0000001510522673__li31274274281"><strong id="EN-US_TOPIC_0000001510522673__b1937183110201">on</strong> indicates that a Mixed Agg query plan is generated for the Grouping Sets statement (including Rollup or Cube) that meets certain conditions.</li><li id="EN-US_TOPIC_0000001510522673__li11127112711288"><strong id="EN-US_TOPIC_0000001510522673__b23200536">off</strong> indicates it is disabled.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__p11127122742815"><strong id="EN-US_TOPIC_0000001510522673__b12529164011219">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b1553017401219">off</strong></p>
<div class="notice" id="EN-US_TOPIC_0000001510522673__note698065711512"><span class="noticetitle"><img src="public_sys-resources/notice_3.0-en-us.png"> </span><div class="noticebody"><p id="EN-US_TOPIC_0000001510522673__p1079913282434">The Mixed Agg query plan can be used to improve the performance of statements dealing with a large amount of data (the data volume of a single DN table is greater than 100 GB).</p>
<p id="EN-US_TOPIC_0000001510522673__p1398185718510">Mixed Agg is not supported in the following scenarios:</p>
<ul id="EN-US_TOPIC_0000001510522673__ul119819577511"><li id="EN-US_TOPIC_0000001510522673__li89815571513">The data type of the columns in the <strong id="EN-US_TOPIC_0000001510522673__b0400131214243">GROUP BY</strong> clause do not support hashing.</li><li id="EN-US_TOPIC_0000001510522673__li13408947191118">The aggregate function uses <strong id="EN-US_TOPIC_0000001510522673__b19509163072416">DISTINCT</strong> for deduplication or <strong id="EN-US_TOPIC_0000001510522673__b1379253222413">ORDER BY</strong> for sorting.</li><li id="EN-US_TOPIC_0000001510522673__li1911151444314">The <strong id="EN-US_TOPIC_0000001510522673__b172183916245">GROUPING SETS</strong> clause does not contain empty groups.</li></ul>
</div></div>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__s99d549c6e4364cd9b4424c14ba0229fe"><h4 class="sectiontitle">enable_hashjoin</h4><p id="EN-US_TOPIC_0000001510522673__a51f63ff195204e92a892468f869f55a3"><strong id="EN-US_TOPIC_0000001510522673__b5346136693">Parameter description</strong>: Controls whether the query optimizer uses the Hash-join plan type.</p>
<p id="EN-US_TOPIC_0000001510522673__p062113115263"><strong id="EN-US_TOPIC_0000001510522673__b9653681124">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__a57e6585946314838be9b04c834abb735"><strong id="EN-US_TOPIC_0000001510522673__b1592316215214">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001510522673__u97d1d12ca9d5421ca9786b8cc0b4f129"><li id="EN-US_TOPIC_0000001510522673__l87a85d137f3742689034f608b6bb6fff"><strong id="EN-US_TOPIC_0000001510522673__b12901142232117">on</strong> indicates it is enabled.</li><li id="EN-US_TOPIC_0000001510522673__lc46a77bf3b76490aa750760692cb6947"><strong id="EN-US_TOPIC_0000001510522673__b617142416218">off</strong> indicates it is disabled.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__aaddc60b59cfb425888e824fa2c2e80fe"><strong id="EN-US_TOPIC_0000001510522673__b12834224162114">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b148341724182111">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__s9dc36ace96544fda934bb7954e566fdc"><h4 class="sectiontitle">enable_indexscan</h4><p id="EN-US_TOPIC_0000001510522673__a47f2cb95851a42dc9bb7b327884ae14c"><strong id="EN-US_TOPIC_0000001510522673__b529421151919">Parameter description</strong>: Controls whether the query optimizer uses the index-scan plan type.</p>
<p id="EN-US_TOPIC_0000001510522673__p9560131082619"><strong id="EN-US_TOPIC_0000001510522673__b38668871216">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__a8f26b472e7e74133b1eb592a13e1f09b"><strong id="EN-US_TOPIC_0000001510522673__b38401025202115">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001510522673__u349a1e7f29fc49f898e71d0b722a9d46"><li id="EN-US_TOPIC_0000001510522673__lb9cfd69359114f2eb79cdb1ca72a5d7f"><strong id="EN-US_TOPIC_0000001510522673__b1381592672116">on</strong> indicates it is enabled.</li><li id="EN-US_TOPIC_0000001510522673__ld5656fd0bd5048969afc5e734c3b9f3c"><strong id="EN-US_TOPIC_0000001510522673__b36981427192118">off</strong> indicates it is disabled.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__a3493b947c40b4c498804ea573ee24a77"><strong id="EN-US_TOPIC_0000001510522673__b764110280218">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b364192815216">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__sb0947e54fce74d5cbae91de6dbe43364"><h4 class="sectiontitle">enable_indexonlyscan</h4><p id="EN-US_TOPIC_0000001510522673__a7b01140bbe1d4310a72d5126864f9145"><strong id="EN-US_TOPIC_0000001510522673__b1485623415197">Parameter description</strong>: Controls whether the query optimizer uses the index-only-scan plan type.</p>
<p id="EN-US_TOPIC_0000001510522673__p11537201862614"><strong id="EN-US_TOPIC_0000001510522673__b18541597122">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__a081ada0222344683bd8f9d26323eff11"><strong id="EN-US_TOPIC_0000001510522673__b1546542915218">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001510522673__u7c6dd66eb9824652b4bebf5385876c51"><li id="EN-US_TOPIC_0000001510522673__l7540a0be7eb74a0bbc06120b9d8a32d9"><strong id="EN-US_TOPIC_0000001510522673__b17534183082118">on</strong> indicates it is enabled.</li><li id="EN-US_TOPIC_0000001510522673__lf791df992e924e649a702fd4b5172d5d"><strong id="EN-US_TOPIC_0000001510522673__b20518631142118">off</strong> indicates it is disabled.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__aedf7a46da03f49bb8ba742131229b612"><strong id="EN-US_TOPIC_0000001510522673__b5615432102118">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b19616113262112">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__s154630d1b7a9430b8a8af02779d56078"><h4 class="sectiontitle">enable_material</h4><p id="EN-US_TOPIC_0000001510522673__a2b12adc9025b418a96c17953642467ef"><strong id="EN-US_TOPIC_0000001510522673__b3433181419203">Parameter description</strong>: Controls whether the query optimizer uses materialization. It is impossible to suppress materialization entirely, but setting this parameter to <strong id="EN-US_TOPIC_0000001510522673__b948853837162936">off</strong> prevents the optimizer from inserting materialized nodes.</p>
<p id="EN-US_TOPIC_0000001510522673__p1334832717267"><strong id="EN-US_TOPIC_0000001510522673__b21982921217">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__aef434c6ecedf41ca9ee3b8c2bbc2ee44"><strong id="EN-US_TOPIC_0000001510522673__b1431113332117">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001510522673__u57ab4d99caae468b93acd9f64dc9330d"><li id="EN-US_TOPIC_0000001510522673__l5939ba51dccb4fd5a94a9bf40e3b80cb"><strong id="EN-US_TOPIC_0000001510522673__b193680342216">on</strong> indicates it is enabled.</li><li id="EN-US_TOPIC_0000001510522673__l12e155b3e6f44cb3a374088aead59721"><strong id="EN-US_TOPIC_0000001510522673__b743414357214">off</strong> indicates it is disabled.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__a055c8e5bd8094bf3bcca93fb2a3c9635"><strong id="EN-US_TOPIC_0000001510522673__b1447017366213">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b1247015360215">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__sfd907746eb8144138a76026cb15b15c7"><h4 class="sectiontitle">enable_mergejoin</h4><p id="EN-US_TOPIC_0000001510522673__a4b5e5b3400af4afa8e1ef9265d5955c5"><strong id="EN-US_TOPIC_0000001510522673__b1311703282115">Parameter description</strong>: Controls whether the query optimizer uses the merge-join plan type.</p>
<p id="EN-US_TOPIC_0000001510522673__p48113713263"><strong id="EN-US_TOPIC_0000001510522673__b13374196128">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__a4fcf70191c0d472b8dfe68fb28fd03fc"><strong id="EN-US_TOPIC_0000001510522673__b14487137122118">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001510522673__u0141d3ba7cb34e9a9141261e88375a6b"><li id="EN-US_TOPIC_0000001510522673__l20c8751fb54f49b0b5dac30deefa9731"><strong id="EN-US_TOPIC_0000001510522673__b35151638132111">on</strong> indicates it is enabled.</li><li id="EN-US_TOPIC_0000001510522673__l44f836bfcbae4a09913ebc0b34b74560"><strong id="EN-US_TOPIC_0000001510522673__b1045633932114">off</strong> indicates it is disabled.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__ae0d999cedb914cb3989a08714395c107"><strong id="EN-US_TOPIC_0000001510522673__b1183047945">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b1198898227">off</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__s1bef702ce82b497eb5a4a69f47a13a10"><h4 class="sectiontitle">enable_nestloop</h4><p id="EN-US_TOPIC_0000001510522673__aea64a8a96c74429d9afbe1f4b4eee993"><strong id="EN-US_TOPIC_0000001510522673__b10360172971117">Parameter description</strong>: Controls whether the query optimizer uses the nested-loop join plan type to fully scan internal tables. It is impossible to suppress nested-loop joins entirely, but setting this parameter to <strong id="EN-US_TOPIC_0000001510522673__en-us_topic_0059778346_en-us_topic_0058967673_b60095344152658">off</strong> allows the optimizer to choose other methods if available.</p>
<p id="EN-US_TOPIC_0000001510522673__p1569917451261"><strong id="EN-US_TOPIC_0000001510522673__b195529971213">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__ad4bc105fd5174e2cb533c466f58771a3"><strong id="EN-US_TOPIC_0000001510522673__b18444154111213">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001510522673__u8f60fadc48a74b66ae4aca46f54f129e"><li id="EN-US_TOPIC_0000001510522673__l3c7c268553474161afe812de75628a7d"><strong id="EN-US_TOPIC_0000001510522673__b262144292112">on</strong> indicates it is enabled.</li><li id="EN-US_TOPIC_0000001510522673__l268ebe7ef3684073a6bcad5952af7566"><strong id="EN-US_TOPIC_0000001510522673__b278318435217">off</strong> indicates it is disabled.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__a7f9c0e81ef3b4e70ad08a291e9dcebb1"><strong id="EN-US_TOPIC_0000001510522673__b16653134422118">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b365404415218">off</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__section1584803291014"><h4 class="sectiontitle">enable_index_nestloop</h4><p id="EN-US_TOPIC_0000001510522673__p862223691014"><strong id="EN-US_TOPIC_0000001510522673__b1818584515120">Parameter description</strong>: Controls whether the query optimizer uses the nested-loop join plan type to scan the parameterized indexes of internal tables.</p>
<p id="EN-US_TOPIC_0000001510522673__p268912202720"><strong id="EN-US_TOPIC_0000001510522673__b108071591123">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__p6483286691014"><strong id="EN-US_TOPIC_0000001510522673__en-us_topic_0059778871_en-us_topic_0058967732_b10741640_1">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001510522673__ul1697081291014"><li id="EN-US_TOPIC_0000001510522673__li1851958391014"><strong id="EN-US_TOPIC_0000001510522673__b84510594127">on</strong> indicates the query optimizer uses the nested-loop join plan type.</li><li id="EN-US_TOPIC_0000001510522673__li3245852291014"><strong id="EN-US_TOPIC_0000001510522673__b1081041281319">off</strong> indicates the query optimizer does not use the nested-loop join plan type.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__p99851452104214"><strong id="EN-US_TOPIC_0000001510522673__b81176504579">Default value</strong>: The default value for a newly installed cluster is <strong id="EN-US_TOPIC_0000001510522673__b21173505575">on</strong>. If the cluster is upgraded from R8C10, the forward compatibility is retained. If the version is upgraded from R7C10 or an earlier version, the default value is <strong id="EN-US_TOPIC_0000001510522673__b19410127175820">off</strong>.</p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__sc4e3e214b4354ad680b7147e8c460658"><h4 class="sectiontitle">enable_seqscan</h4><p id="EN-US_TOPIC_0000001510522673__a6716155c25b04ddeb91e286042301734"><strong id="EN-US_TOPIC_0000001510522673__b0555633122216">Parameter description</strong>: Controls whether the query optimizer uses the sequential scan plan type. It is impossible to suppress sequential scans entirely, but setting this variable to <strong id="EN-US_TOPIC_0000001510522673__en-us_topic_0059778346_en-us_topic_0058967673_b41076330152658">off</strong> allows the optimizer to preferentially choose other methods if available.</p>
<p id="EN-US_TOPIC_0000001510522673__p189394210274"><strong id="EN-US_TOPIC_0000001510522673__b175910171211">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__a7c6c308c03ce4d259ac1596bbe056e30"><strong id="EN-US_TOPIC_0000001510522673__b252019455213">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001510522673__u0b50a3e74213486aae0d0aa3201e3473"><li id="EN-US_TOPIC_0000001510522673__l53a46ccc02cb4a648e3089ed325fc879"><strong id="EN-US_TOPIC_0000001510522673__b860314642115">on</strong> indicates it is enabled.</li><li id="EN-US_TOPIC_0000001510522673__l83e91d6809c547fab017c38c201119d4"><strong id="EN-US_TOPIC_0000001510522673__b3385194762112">off</strong> indicates it is disabled.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__ad97d9a1b7325471d89c8e1c57a2289f6"><strong id="EN-US_TOPIC_0000001510522673__b1440310481214">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b3403114818213">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__sdc6a03a94d3743e8a856428f604446c9"><h4 class="sectiontitle">enable_sort</h4><p id="EN-US_TOPIC_0000001510522673__ad163bc65ab2a46c899ee2f2cf1ad973e"><strong id="EN-US_TOPIC_0000001510522673__b8260144182911">Parameter description</strong>: Controls whether the query optimizer uses the sort method. It is impossible to suppress explicit sorts entirely, but setting this variable to <strong id="EN-US_TOPIC_0000001510522673__en-us_topic_0059778346_en-us_topic_0058967673_b22292535152658">off</strong> allows the optimizer to preferentially choose other methods if available.</p>
<p id="EN-US_TOPIC_0000001510522673__p115641322276"><strong id="EN-US_TOPIC_0000001510522673__b1116119104122">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__af060df14d0b14373911d679f8009b46d"><strong id="EN-US_TOPIC_0000001510522673__b937212495219">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001510522673__uf16166d1d6d0473fad1bf487da14dd63"><li id="EN-US_TOPIC_0000001510522673__l23dc33774a364ad59529ccb4c237246d"><strong id="EN-US_TOPIC_0000001510522673__b727395082117">on</strong> indicates it is enabled.</li><li id="EN-US_TOPIC_0000001510522673__l1bf836e102384c38b3230eab301f7372"><strong id="EN-US_TOPIC_0000001510522673__b5291175119212">off</strong> indicates it is disabled.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__a82f1fc8013664bdfa3ef77236f8027b5"><strong id="EN-US_TOPIC_0000001510522673__b10982052152110">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b299252172113">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__s9dc942e0972446d2b2adb1590b43f077"><h4 class="sectiontitle">enable_tidscan</h4><p id="EN-US_TOPIC_0000001510522673__ad094a3fb762b4940b8376c63938611bf"><strong id="EN-US_TOPIC_0000001510522673__b13810173110299">Parameter description</strong>: Controls whether the query optimizer uses the Tuple ID (TID) scan plan type.</p>
<p id="EN-US_TOPIC_0000001510522673__p9707440182719"><strong id="EN-US_TOPIC_0000001510522673__b4312131011126">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__a7032ae392d864a0a838ead04fff628ee"><strong id="EN-US_TOPIC_0000001510522673__b16701953142117">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001510522673__ue4d8cfce487f4c2c9cb889fa47fc01b1"><li id="EN-US_TOPIC_0000001510522673__l2d14d5397a7842bea1898c1006b74f51"><strong id="EN-US_TOPIC_0000001510522673__b149111536219">on</strong> indicates it is enabled.</li><li id="EN-US_TOPIC_0000001510522673__l0f8361f8a5e84a90acd04f8facda640a"><strong id="EN-US_TOPIC_0000001510522673__b1979125412212">off</strong> indicates it is disabled.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__a3dcd7522fae7440682d6bb5b13081af1"><strong id="EN-US_TOPIC_0000001510522673__b1494115514212">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b1194185519211">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__s5da1e5bd74434dcba5b3448d18057102"><h4 class="sectiontitle">enable_kill_query</h4><p id="EN-US_TOPIC_0000001510522673__afca0c49423754aa5a7b1b38a7ee1f641"><strong id="EN-US_TOPIC_0000001510522673__b14916845434656">Parameter description</strong>: In CASCADE mode, when a user is deleted, all the objects belonging to the user are deleted. This parameter specifies whether the queries of the objects belonging to the user can be unlocked when the user is deleted.</p>
<p id="EN-US_TOPIC_0000001510522673__p66828511278"><strong id="EN-US_TOPIC_0000001510522673__b999051081216">Type</strong>: SUSET</p>
<p id="EN-US_TOPIC_0000001510522673__a8cbdba0ede5249f4b1ec7679d1534b56"><strong id="EN-US_TOPIC_0000001510522673__en-us_topic_0059778346_en-us_topic_0058967673_b6625143011450_23">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001510522673__u1daeaac11dac44f28cc29c18750728df"><li id="EN-US_TOPIC_0000001510522673__le69abcd2b42047a3b7922ffe21528cd3"><strong id="EN-US_TOPIC_0000001510522673__b192688057634656">on</strong> indicates the unlocking is allowed.</li><li id="EN-US_TOPIC_0000001510522673__l17ec89e6ef5e4d689a63c082f1de8a5b"><strong id="EN-US_TOPIC_0000001510522673__b140256454434656">off</strong> indicates the unlocking is not allowed.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__a2aa9b9ead2bf4eaeb66c8ed773a1eca5"><strong id="EN-US_TOPIC_0000001510522673__en-us_topic_0059778346_en-us_topic_0058967673_b49259546">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__en-us_topic_0059778346_en-us_topic_0058967673_b84235270611220">off</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__s9d86a26098fc4e0f90cb9d8d91359482"><h4 class="sectiontitle">enforce_oracle_behavior</h4><p id="EN-US_TOPIC_0000001510522673__a9524c4b2154e4f6097dac7bc14be5d53"><strong id="EN-US_TOPIC_0000001510522673__en-us_topic_0059778346_a09e28664a0d347bd9e7f7f2b23539645">Parameter description</strong>: Controls the rule matching modes of regular expressions.</p>
<p id="EN-US_TOPIC_0000001510522673__p839611498289"><strong id="EN-US_TOPIC_0000001510522673__b1319320113126">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__a08948b7c15744058a01f00101649f885"><strong id="EN-US_TOPIC_0000001510522673__en-us_topic_0059778346_en-us_topic_0058967673_b6625143011450_25">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001510522673__u08d008be00774e6fa3f3c85b2bc0bd8c"><li id="EN-US_TOPIC_0000001510522673__lbf08104e9fbe4a39aec173b6847c72f4"><strong id="EN-US_TOPIC_0000001510522673__b13876105173915">on</strong> indicates that the ORACLE matching rule is used.</li><li id="EN-US_TOPIC_0000001510522673__l52949c930c3041f79b96a86bee6c7acf"><strong id="EN-US_TOPIC_0000001510522673__b17792181220417">off</strong> indicates that the POSIX matching rule is used.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__a320abb2b12cc4dd5a1a884a48ce611eb"><strong id="EN-US_TOPIC_0000001510522673__en-us_topic_0059778346_en-us_topic_0058967673_b26996297_1">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__en-us_topic_0059778346_en-us_topic_0058967673_b842352706111724">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__section3886652184817"><h4 class="sectiontitle">enable_stream_concurrent_update</h4><p id="EN-US_TOPIC_0000001510522673__p14886195254818"><strong id="EN-US_TOPIC_0000001510522673__b114961945104314">Parameter description</strong>: Controls the use of <strong id="EN-US_TOPIC_0000001510522673__b574523164615">stream</strong> in concurrent updates. This parameter is restricted by the <a href="#EN-US_TOPIC_0000001510522673__se97ba22fff0144d784f5363903a1f584">enable_stream_operator</a> parameter.</p>
<p id="EN-US_TOPIC_0000001510522673__p1988565710283"><strong id="EN-US_TOPIC_0000001510522673__b163210116123">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__p288816520486"><strong id="EN-US_TOPIC_0000001510522673__en-us_topic_0059778346_en-us_topic_0058967673_b60355922">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001510522673__ul148881952174815"><li id="EN-US_TOPIC_0000001510522673__li1588917529485"><strong id="EN-US_TOPIC_0000001510522673__b1828345544418">on</strong> indicates that the optimizer can generate stream plans for the <strong id="EN-US_TOPIC_0000001510522673__b15375181812456">UPDATE</strong> statement.</li><li id="EN-US_TOPIC_0000001510522673__li588925264817"><strong id="EN-US_TOPIC_0000001510522673__b966772310459">off</strong> indicates that the optimizer can generate only non-stream plans for the <strong id="EN-US_TOPIC_0000001510522673__b13481348144519">UPDATE</strong> statement.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__p488914522488"><strong id="EN-US_TOPIC_0000001510522673__b1824304745">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b321036494">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__section684911518381"><h4 class="sectiontitle">enable_stream_ctescan</h4><p id="EN-US_TOPIC_0000001510522673__p7850555383"><strong id="EN-US_TOPIC_0000001510522673__b1599485231316">Parameter description</strong>: Specifies whether a stream plan supports <strong id="EN-US_TOPIC_0000001510522673__b197678301307">ctescan</strong>.</p>
<p id="EN-US_TOPIC_0000001510522673__p98503593814"><strong id="EN-US_TOPIC_0000001510522673__b042415262148">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__p188501756382"><strong id="EN-US_TOPIC_0000001510522673__b188211274141">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001510522673__ul285095173819"><li id="EN-US_TOPIC_0000001510522673__li585012533813"><strong id="EN-US_TOPIC_0000001510522673__b366564951419">on</strong> indicates that <strong id="EN-US_TOPIC_0000001510522673__b196331636203012">ctescan </strong>is supported for the stream plan.</li><li id="EN-US_TOPIC_0000001510522673__li1985018513389"><strong id="EN-US_TOPIC_0000001510522673__b1164276131515">off</strong> indicates that <strong id="EN-US_TOPIC_0000001510522673__b356134033018">ctescan </strong>is not supported for the stream plan.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__p985055193810"><strong id="EN-US_TOPIC_0000001510522673__b129227592456">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b189231259144519">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__se97ba22fff0144d784f5363903a1f584"><a name="EN-US_TOPIC_0000001510522673__se97ba22fff0144d784f5363903a1f584"></a><a name="se97ba22fff0144d784f5363903a1f584"></a><h4 class="sectiontitle">enable_stream_operator</h4><p id="EN-US_TOPIC_0000001510522673__a15bc037edf79486caebcf9ff70e9c5f4"><strong id="EN-US_TOPIC_0000001510522673__b11295822103012">Parameter description:</strong> Controls whether the query optimizer uses streams.</p>
<p id="EN-US_TOPIC_0000001510522673__p1845717520293"><strong id="EN-US_TOPIC_0000001510522673__b17821191131211">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__a330dd23b039f4f6cbec53bf6d5992a62"><strong id="EN-US_TOPIC_0000001510522673__b1197111314221">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001510522673__u88fc88d8f85d40288ce47c2c9368f896"><li id="EN-US_TOPIC_0000001510522673__lad918382791e4cbd8943adaa06c1e1b7"><strong id="EN-US_TOPIC_0000001510522673__b597015420227">on</strong> indicates it is enabled.</li><li id="EN-US_TOPIC_0000001510522673__l0f9f4ab8d87341fd909820de15d9ec74"><strong id="EN-US_TOPIC_0000001510522673__b73515617222">off</strong> indicates it is disabled.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__a24c301487204418abd758704789aff13"><strong id="EN-US_TOPIC_0000001510522673__b1988812615228">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b988856112213">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__section141901419113317"><h4 class="sectiontitle">enable_stream_recursive</h4><p id="EN-US_TOPIC_0000001510522673__p8190119193320"><strong id="EN-US_TOPIC_0000001510522673__b77821242469">Parameter description</strong>: Specifies whether to push <strong id="EN-US_TOPIC_0000001510522673__b37821745465">WITH RECURSIVE</strong> join queries to DNs for processing.</p>
<p id="EN-US_TOPIC_0000001510522673__p573851516290"><strong id="EN-US_TOPIC_0000001510522673__b399151111217">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__p1219081973315"><strong id="EN-US_TOPIC_0000001510522673__b1987006328">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001510522673__ul91901019103316"><li id="EN-US_TOPIC_0000001510522673__li6190219193313"><strong id="EN-US_TOPIC_0000001510522673__b4381356461">on</strong>: <strong id="EN-US_TOPIC_0000001510522673__b153873516468">WITH RECURSIVE</strong> join queries will be pushed down to DNs.</li><li id="EN-US_TOPIC_0000001510522673__li151901019123312"><strong id="EN-US_TOPIC_0000001510522673__b1019053714463">off</strong>: <strong id="EN-US_TOPIC_0000001510522673__b519017379465">WITH RECURSIVE</strong> join queries will not be pushed down to DNs.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__p5190019173317"><strong id="EN-US_TOPIC_0000001510522673__b321958534">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b302730921">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__section93801341534"><h4 class="sectiontitle">enable_value_redistribute</h4><p id="EN-US_TOPIC_0000001510522673__p163801534634"><strong id="EN-US_TOPIC_0000001510522673__b8319115812414">Parameter description</strong>: Specifies whether to generate value redistribute plans. In 8.2.0 and later cluster versions, this parameter takes effect for <strong id="EN-US_TOPIC_0000001510522673__b59064122818">rank</strong>, <strong id="EN-US_TOPIC_0000001510522673__b1858910421282">dense_rank</strong>, and <strong id="EN-US_TOPIC_0000001510522673__b688315538286">row_number</strong> without the <strong id="EN-US_TOPIC_0000001510522673__b698814567284">PARTITION BY</strong> clause.</p>
<p id="EN-US_TOPIC_0000001510522673__p113801341438"><strong id="EN-US_TOPIC_0000001510522673__b1811575592">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__p10380134732"><strong id="EN-US_TOPIC_0000001510522673__b521415345">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001510522673__ul338016341637"><li id="EN-US_TOPIC_0000001510522673__li203809341535"><strong id="EN-US_TOPIC_0000001510522673__b121212160259">on</strong> indicates that value redistribute plans are generated.</li><li id="EN-US_TOPIC_0000001510522673__li23801734931"><strong id="EN-US_TOPIC_0000001510522673__b2095007268">off</strong> indicates that no value redistribute plans are generated.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__p73801834232"><strong id="EN-US_TOPIC_0000001510522673__b1940975369">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b1224655215">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__section333410396346"><h4 class="sectiontitle">max_recursive_times</h4><p id="EN-US_TOPIC_0000001510522673__p16334183983417"><strong id="EN-US_TOPIC_0000001510522673__b03713400710">Parameter description</strong>: Specifies the maximum number of <strong id="EN-US_TOPIC_0000001510522673__b1637212404712">WITH RECURSIVE</strong> iterations.</p>
<p id="EN-US_TOPIC_0000001510522673__p11184824112915"><strong id="EN-US_TOPIC_0000001510522673__b4150201271214">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__p11226150183517"><strong id="EN-US_TOPIC_0000001510522673__b102266023511">Value range</strong>: an integer ranging from 0 to INT_MAX</p>
<p id="EN-US_TOPIC_0000001510522673__p15334203914348"><strong id="EN-US_TOPIC_0000001510522673__b19441124916719">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b44441491971">200</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__sb6526e37d99f4be8a9dc9b4739a76077"><h4 class="sectiontitle">enable_vector_engine</h4><p id="EN-US_TOPIC_0000001510522673__a1f79cf6106db443cafdb19a7f735f92a"><strong id="EN-US_TOPIC_0000001510522673__b1826611718311">Parameter description</strong>: Controls whether the query optimizer uses the vectorized executor.</p>
<p id="EN-US_TOPIC_0000001510522673__p16168442172916"><strong id="EN-US_TOPIC_0000001510522673__b193381112101214">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__a9b0b6101f0364471b616207ba6f70631"><strong id="EN-US_TOPIC_0000001510522673__b199792711227">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001510522673__u1d0b3c41b1dd4deaa1fd713dcb5438ad"><li id="EN-US_TOPIC_0000001510522673__l1b83edbe0f9b4cb48674b9ad3d6699f0"><strong id="EN-US_TOPIC_0000001510522673__b118075872214">on</strong> indicates it is enabled.</li><li id="EN-US_TOPIC_0000001510522673__l6351e66e45834c4f9a2fd8b3f4de4de3"><strong id="EN-US_TOPIC_0000001510522673__b1875213910224">off</strong> indicates it is disabled.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__a0e8a3b85d75e41e4a813ee56b5125d66"><strong id="EN-US_TOPIC_0000001510522673__b8656171015224">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b1865641011228">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__s4500e9c69a874ebf84590371d8404791"><h4 class="sectiontitle">enable_broadcast</h4><p id="EN-US_TOPIC_0000001510522673__add4fba2275bb465bba1e99c8711f985d"><strong id="EN-US_TOPIC_0000001510522673__en-us_topic_0059778346_en-us_topic_0058967673_b842352706201758">Parameter description</strong>: Controls whether the query optimizer uses the broadcast distribution method when it evaluates the cost of stream.</p>
<p id="EN-US_TOPIC_0000001510522673__p1642264982916"><strong id="EN-US_TOPIC_0000001510522673__b14511111281213">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__ab95d4efb036e4cad9dcf096fe371bfad"><strong id="EN-US_TOPIC_0000001510522673__b175851311112210">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001510522673__uf9e97ee192b34a73b21161a64e803e33"><li id="EN-US_TOPIC_0000001510522673__l03543e4d30264764987df824ea90f8b8"><strong id="EN-US_TOPIC_0000001510522673__b1838120121223">on</strong> indicates it is enabled.</li><li id="EN-US_TOPIC_0000001510522673__le54c9c99f136451dbe66d26278955021"><strong id="EN-US_TOPIC_0000001510522673__b5369191322219">off</strong> indicates it is disabled.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__adbfd042a91344a4383fe39ac763c3925"><strong id="EN-US_TOPIC_0000001510522673__b1663171416228">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b46325147221">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__section373014243501"><h4 class="sectiontitle">enable_redistribute</h4><p id="EN-US_TOPIC_0000001510522673__p12730112413501"><strong id="EN-US_TOPIC_0000001510522673__b2684951705">Parameter description</strong>: Controls whether the query optimizer uses the local redistribute or split redistribute distribution method when estimating the cost of streams. This parameter is supported only by clusters of version 8.2.1.300 or later.</p>
<p id="EN-US_TOPIC_0000001510522673__p57301924125018"><strong id="EN-US_TOPIC_0000001510522673__b467431463">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__p2073092455013"><strong id="EN-US_TOPIC_0000001510522673__b525366338">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001510522673__ul17730152416505"><li id="EN-US_TOPIC_0000001510522673__li1973015240506"><strong id="EN-US_TOPIC_0000001510522673__b5233210663">on</strong> indicates that either of the distribution methods is used.</li><li id="EN-US_TOPIC_0000001510522673__li67301124165017"><strong id="EN-US_TOPIC_0000001510522673__b953515357717">off</strong> indicates that none of the distribution methods is used.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__p197308248506"><strong id="EN-US_TOPIC_0000001510522673__b1611327112">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b1491858635">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__sa3d7337362cf4789bf45cc4ee30dc475"><h4 class="sectiontitle">enable_change_hjcost</h4><p id="EN-US_TOPIC_0000001510522673__afe9b1d31dec14cc1ab573802b736526c"><strong id="EN-US_TOPIC_0000001510522673__en-us_topic_0059778346_en-us_topic_0058967673_b842352706978">Parameter description</strong>: Specifies whether the optimizer excludes internal table running costs when selecting the Hash Join cost path. If it is set to <strong id="EN-US_TOPIC_0000001510522673__en-us_topic_0059778346_en-us_topic_0058967673_b842352706155359">on</strong>, tables with a few records and high running costs are more possible to be selected.</p>
<p id="EN-US_TOPIC_0000001510522673__p374810105307"><strong id="EN-US_TOPIC_0000001510522673__b1277364925814">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__a673709746e654a8bb0e14ceff634419f"><strong id="EN-US_TOPIC_0000001510522673__b254011518228">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001510522673__u4a13fa5f7e964977bcdafca2b3c03df1"><li id="EN-US_TOPIC_0000001510522673__l55e8d4f5bfcb465a89396c9371e50320"><strong id="EN-US_TOPIC_0000001510522673__b1648421672210">on</strong> indicates it is enabled.</li><li id="EN-US_TOPIC_0000001510522673__l0244d9b980f74674835c3ead6a0831aa"><strong id="EN-US_TOPIC_0000001510522673__b742111174228">off</strong> indicates it is disabled.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__a2c5cecfe26644356a768f80449393080"><strong id="EN-US_TOPIC_0000001510522673__b8259218122217">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b22601218152217">off</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__s4dab13535595427c962b6199de100d91"><h4 class="sectiontitle">enable_fstream</h4><p id="EN-US_TOPIC_0000001510522673__a72bed8b7151d4dcda16481b7197790d3"><strong id="EN-US_TOPIC_0000001510522673__en-us_topic_0059778346_en-us_topic_0058967673_b84235270691356">Parameter description</strong>: Controls whether the query optimizer uses streams when it delivers statements. This parameter is only used for external HDFS tables.</p>
<p id="EN-US_TOPIC_0000001510522673__adb187ad07a7843e38309d96bbf10cc4c">This parameter has been discarded. To reserve forward compatibility, set this parameter to <strong id="EN-US_TOPIC_0000001510522673__b20396203610910">on</strong>, but the setting does not make a difference.</p>
<p id="EN-US_TOPIC_0000001510522673__p10800824133016"><strong id="EN-US_TOPIC_0000001510522673__b1389891251217">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__aec600014105848b9aede8a3c1afbf6c0"><strong id="EN-US_TOPIC_0000001510522673__b16258719112218">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001510522673__uf4e8e760bcbc4574be9752da25fdc247"><li id="EN-US_TOPIC_0000001510522673__lcfda252151d049ec856602726f3e14da"><strong id="EN-US_TOPIC_0000001510522673__b1920912017227">on</strong> indicates it is enabled.</li><li id="EN-US_TOPIC_0000001510522673__l0ced2bb93a0349dc836583ea80beacbf"><strong id="EN-US_TOPIC_0000001510522673__b09671920132212">off</strong> indicates it is disabled.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__a30e06ee1c5ff45fbaa684eec054e2b96"><strong id="EN-US_TOPIC_0000001510522673__b12361543">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b1708295829">off</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__section4272172816241"><h4 class="sectiontitle">enable_hashfilter</h4><p id="EN-US_TOPIC_0000001510522673__p142721128162412"><strong id="EN-US_TOPIC_0000001510522673__b13674152218512">Parameter description</strong>: Controls whether hashfilters can be generated for plans that contain replication tables (including dual and constant tables). This parameter is supported by version 8.2.0 or later clusters.</p>
<p id="EN-US_TOPIC_0000001510522673__p15272172842412"><strong id="EN-US_TOPIC_0000001510522673__b1397412377510">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__p11272172816241"><strong id="EN-US_TOPIC_0000001510522673__b4200184119512">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001510522673__ul612042243216"><li id="EN-US_TOPIC_0000001510522673__li4120922163217"><strong id="EN-US_TOPIC_0000001510522673__b1976064418511">on</strong> indicates that hashfilters can be generated.</li><li id="EN-US_TOPIC_0000001510522673__li16212256324"><strong id="EN-US_TOPIC_0000001510522673__b1840064810518">off</strong> indicates that no hashfilters can be generated.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__p165053712249"><strong id="EN-US_TOPIC_0000001510522673__b1250212118615">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b212271043142518">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__s3d76d6e1b1804c148ec9df86569ff5b7"><h4 class="sectiontitle">best_agg_plan</h4><div class="p" id="EN-US_TOPIC_0000001510522673__ada3283facf984429b50f00d7501ea286"><strong id="EN-US_TOPIC_0000001510522673__en-us_topic_0059778346_en-us_topic_0058967673_b84235270692319">Parameter description</strong>: The query optimizer generates three plans for the aggregate operation under the stream:<ol id="EN-US_TOPIC_0000001510522673__o2fc6c049bba74dd1be921e303b3386cc"><li id="EN-US_TOPIC_0000001510522673__l5c4e3d28ce8047a49b90beb7b9baadd0">hashagg+gather(redistribute)+hashagg</li><li id="EN-US_TOPIC_0000001510522673__le0e3e33df31349e8904f4a94c677c07d">redistribute+hashagg(+gather)</li><li id="EN-US_TOPIC_0000001510522673__l2b8b7e8ded5f406a8c4cfebae9845f58">hashagg+redistribute+hashagg(+gather).</li></ol>
</div>
<p id="EN-US_TOPIC_0000001510522673__a0079f0fa868d45a1ab69c74c8ffe975e">This parameter is used to control the query optimizer to generate which type of hashagg plans.</p>
<p id="EN-US_TOPIC_0000001510522673__p01172014133120"><strong id="EN-US_TOPIC_0000001510522673__b01621310122">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__a260a2b8c442c49e08530df3b0ba1f3db"><strong id="EN-US_TOPIC_0000001510522673__en-us_topic_0059778346_en-us_topic_0058967673_b66499804">Value range</strong>: an integer ranging from 0 to 3.</p>
<ul id="EN-US_TOPIC_0000001510522673__u3f6854a7b6f544ea98b24fefa622a447"><li id="EN-US_TOPIC_0000001510522673__le9e06f01e091426682ed144d8438787e">When the value is set to <strong id="EN-US_TOPIC_0000001510522673__b93285805111552">1</strong>, the first plan is forcibly generated.</li><li id="EN-US_TOPIC_0000001510522673__l4ff4f36f60d74e81bb7795d463b217ef">When the value is set to <strong id="EN-US_TOPIC_0000001510522673__b102009829511538">2</strong> and if the <strong id="EN-US_TOPIC_0000001510522673__b173301864011538">group by</strong> column can be redistributed, the second plan is forcibly generated. Otherwise, the first plan is generated.</li><li id="EN-US_TOPIC_0000001510522673__lc8704bd8068d423a8ef41f61c804a5ba">When the value is set to <strong id="EN-US_TOPIC_0000001510522673__b52680902711522">3</strong> and if the <strong id="EN-US_TOPIC_0000001510522673__b203914458711522">group by</strong> column can be redistributed, the third plan is generated. Otherwise, the first plan is generated.</li><li id="EN-US_TOPIC_0000001510522673__l297286a8e0524e668133af48de3556e4">When the value is set to <strong id="EN-US_TOPIC_0000001510522673__b84235270694450">0</strong>, the query optimizer chooses the most optimal plan based on the estimated costs of the three plans above.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__ae54108f6f4724d1596626a133ab8af18"><strong id="EN-US_TOPIC_0000001510522673__en-us_topic_0059778346_en-us_topic_0058967673_b455675178231">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__en-us_topic_0059778346_en-us_topic_0058967673_b842352706114645">0</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__section27765584720"><h4 class="sectiontitle">index_selectivity_cost</h4><p id="EN-US_TOPIC_0000001510522673__p47795517474"><strong id="EN-US_TOPIC_0000001510522673__b824381912581">Parameter description</strong>: controls the cost calculation (selection rate &gt; 0.001) of cbtree during the scan of column-store table indexes. This parameter is supported only by clusters of version 8.2.1.100 or later.</p>
<p id="EN-US_TOPIC_0000001510522673__p1077115544712"><strong id="EN-US_TOPIC_0000001510522673__b239294844">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__p1777195519473">Value range: a floating point, which can be -1 or ranges from 0 to 1000.</p>
<ul id="EN-US_TOPIC_0000001510522673__ul17805517478"><li id="EN-US_TOPIC_0000001510522673__li11787558478">If this parameter is set to <strong id="EN-US_TOPIC_0000001510522673__b12511618122814">0</strong>, the index selection rate is not affected by the threshold 0.001.</li><li id="EN-US_TOPIC_0000001510522673__li15753369317">If the value is <strong id="EN-US_TOPIC_0000001510522673__b847495193110">-1</strong>, the value is affected by <strong id="EN-US_TOPIC_0000001510522673__b15850454143116">disable_cost</strong>.</li><li id="EN-US_TOPIC_0000001510522673__li127811554474">When it is set to other values, the value is the coefficient for cbtree cost calculation.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__p578125512475">Default value: <strong id="EN-US_TOPIC_0000001510522673__b132054580286">-1</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__section18451241161811"><h4 class="sectiontitle">index_cost_limit</h4><p id="EN-US_TOPIC_0000001510522673__p18846134101817"><strong id="EN-US_TOPIC_0000001510522673__b1016533411326">Parameter description</strong>: threshold for disabling the cost calculation of cbtree during column-store table index scanning. This parameter is supported only by clusters of version 8.2.1.100 or later.</p>
<p id="EN-US_TOPIC_0000001510522673__p68461341161811"><strong id="EN-US_TOPIC_0000001510522673__b1649197721">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__p76611811122011"><strong id="EN-US_TOPIC_0000001510522673__b829113374298">Value range</strong>: an integer ranging from 0 to 2147483647</p>
<ul id="EN-US_TOPIC_0000001510522673__ul158461541171817"><li id="EN-US_TOPIC_0000001510522673__li26761502112">If the value is <strong id="EN-US_TOPIC_0000001510522673__b1228185552916">0</strong>, the parameter does not take effect.</li><li id="EN-US_TOPIC_0000001510522673__li11307102213214">If this parameter is set to other values and the number of rows in a table is less than the value of this parameter, the table is not affected by the index selection rate threshold 0.001.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__p148471441121817"><strong id="EN-US_TOPIC_0000001510522673__b97181095">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b1830339169">0</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__section1616504115207"><h4 class="sectiontitle">volatile_shipping_version</h4><p id="EN-US_TOPIC_0000001510522673__p1316511419206"><strong id="EN-US_TOPIC_0000001510522673__b3119115967">Parameter description</strong>: Controls the execution scope of volatile functions to be pushed down. This parameter is supported by version 8.2.0 or later clusters.</p>
<p id="EN-US_TOPIC_0000001510522673__p7166144119207"><strong id="EN-US_TOPIC_0000001510522673__b1229532096">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__p7166741132010"><strong id="EN-US_TOPIC_0000001510522673__b186975151414">Value range</strong>: an integer ranging from 0 to 3.</p>
<ul id="EN-US_TOPIC_0000001510522673__ul1716694112201"><li id="EN-US_TOPIC_0000001510522673__li1563692316260">At value <strong id="EN-US_TOPIC_0000001510522673__b1251241153713">3</strong>, in addition to the capabilities of value <strong id="EN-US_TOPIC_0000001510522673__b9523104319374">2</strong>, inline CTEs can be pushed down if referenced only once. This value is supported only by clusters of version 8.2.1.105 or later.</li><li id="EN-US_TOPIC_0000001510522673__li184726262218">At value <strong id="EN-US_TOPIC_0000001510522673__b29578149389">2</strong>, besides the features of value <strong id="EN-US_TOPIC_0000001510522673__b15946181718380">1</strong>, pushdown is enabled for CTEs containing VOLATILE functions in the target column.</li><li id="EN-US_TOPIC_0000001510522673__li9166174122018">At value <strong id="EN-US_TOPIC_0000001510522673__b16156185917384">1</strong>, along with the functionalities of value <strong id="EN-US_TOPIC_0000001510522673__b22447113918">0</strong>, the <strong id="EN-US_TOPIC_0000001510522673__b87812028575">nextval</strong>,<strong id="EN-US_TOPIC_0000001510522673__b1529413010711"> uuid_generate_v1</strong>, <strong id="EN-US_TOPIC_0000001510522673__b1431212357718">sys_guid</strong>, and <strong id="EN-US_TOPIC_0000001510522673__b1661219381716">uuid</strong> functions can be fully pushed down if they appear in the target column.</li><li id="EN-US_TOPIC_0000001510522673__li1216616414200">If this parameter is set to <strong id="EN-US_TOPIC_0000001510522673__b6977381813">0</strong>, random functions can be completely pushed down. The <strong id="EN-US_TOPIC_0000001510522673__b7815415101116">nextval</strong> and <strong id="EN-US_TOPIC_0000001510522673__b2458322191119">uuid_generate_v1</strong> functions can be pushed down only if <strong id="EN-US_TOPIC_0000001510522673__b20362102714115">INSERT</strong> contains simple query statements.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__p151666412209"><strong id="EN-US_TOPIC_0000001510522673__b14160643547">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b816064310412">3</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__s07f6d660ef88443aba81be9841fb2449"><h4 class="sectiontitle">agg_redistribute_enhancement</h4><p id="EN-US_TOPIC_0000001510522673__a2667108f1a134936b390980dd4d8f8ab"><strong id="EN-US_TOPIC_0000001510522673__en-us_topic_0059778346_en-us_topic_0058967673_b84235270694930">Parameter description</strong>: When the aggregate operation is performed, which contains multiple <strong id="EN-US_TOPIC_0000001510522673__en-us_topic_0059778346_en-us_topic_0058967673_b84235270695020">group by</strong> columns and all of the columns are not in the distribution column, you need to select one <strong id="EN-US_TOPIC_0000001510522673__en-us_topic_0059778346_en-us_topic_0058967673_b84235270695323">group by</strong> column for redistribution. This parameter controls the policy of selecting a redistribution column.</p>
<p id="EN-US_TOPIC_0000001510522673__p106451222113118"><strong id="EN-US_TOPIC_0000001510522673__b1918301318127">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__a429363b0f0cc42f1b81e10076c4ac95d"><strong id="EN-US_TOPIC_0000001510522673__en-us_topic_0059778346_en-us_topic_0058967673_b6625143011450_37">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001510522673__u90753ae1a3cc425cbc1998b3f05a5f29"><li id="EN-US_TOPIC_0000001510522673__la4f3abf671a04f71b07ae66864d7b675"><strong id="EN-US_TOPIC_0000001510522673__en-us_topic_0059778346_en-us_topic_0058967673_b8423527061003">on</strong> indicates the column that can be redistributed and evaluates the most distinct value for redistribution.</li><li id="EN-US_TOPIC_0000001510522673__la5e539e18c594bd784954f6b58779bbe"><strong id="EN-US_TOPIC_0000001510522673__en-us_topic_0059778346_en-us_topic_0058967673_b8423527061031">off</strong> indicates the first column that can be redistributed for redistribution.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__a83d49873cd6e4c7c9525f544c8dffe18"><strong id="EN-US_TOPIC_0000001510522673__b835830121">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b659505620">off</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__sa17caa9eb29547669e8d2fe19f4321c8"><h4 class="sectiontitle">enable_valuepartition_pruning</h4><p id="EN-US_TOPIC_0000001510522673__a05b27236bf584cd1b2d48f74f8c253ad"><strong id="EN-US_TOPIC_0000001510522673__en-us_topic_0059778346_b1569690523111828">Parameter description</strong>: Specifies whether the DFS partitioned table is dynamically or statically optimized.</p>
<p id="EN-US_TOPIC_0000001510522673__p38994153112"><strong id="EN-US_TOPIC_0000001510522673__b1249619130127">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__a7e3e95d8cd474c1bb2e328bb654307bd"><strong id="EN-US_TOPIC_0000001510522673__en-us_topic_0059778346_b17431449101331">Value range:</strong> Boolean</p>
<ul id="EN-US_TOPIC_0000001510522673__u29a168ea3e8b4921a7c9d64de7294eb5"><li id="EN-US_TOPIC_0000001510522673__l83a1f21d7c3646f6b800a219734523e8"><strong id="EN-US_TOPIC_0000001510522673__b934261178">on</strong> indicates that the DFS partitioned table is dynamically or statically optimized.</li><li id="EN-US_TOPIC_0000001510522673__l8fe473b282e245dcab5f31477fb15689"><strong id="EN-US_TOPIC_0000001510522673__b1120656203">off</strong> indicates that the DFS partitioned table is not dynamically or statically optimized.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__aa3e4cfa9730e43759718983f8958a8cf"><strong id="EN-US_TOPIC_0000001510522673__b457591237">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b1202343148">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__section746841514523"><a name="EN-US_TOPIC_0000001510522673__section746841514523"></a><a name="section746841514523"></a><h4 class="sectiontitle">expected_computing_nodegroup</h4><p id="EN-US_TOPIC_0000001510522673__p99241701345"><strong id="EN-US_TOPIC_0000001510522673__b2092416053419">Parameter description</strong>: Specifies a computing Node Group or the way to choose such a group. The Node Group mechanism is now for internal use only. You do not need to set it.</p>
<p id="EN-US_TOPIC_0000001510522673__p98131843917">During join or aggregation operations, a Node Group can be selected in four modes. In each mode, the specified candidate computing Node Groups are listed for the optimizer to select an appropriate one for the current operator.</p>
<p id="EN-US_TOPIC_0000001510522673__p14297105043110"><strong id="EN-US_TOPIC_0000001510522673__b66711213171217">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__a3d8c820d08c0489ba6c10a47476f8b23"><strong id="EN-US_TOPIC_0000001510522673__en-us_topic_0059777791_en-us_topic_0058967586_b688672095621">Value range</strong>: a string</p>
<ul id="EN-US_TOPIC_0000001510522673__u582a49208d014b459af16e68a402d6df"><li id="EN-US_TOPIC_0000001510522673__l809bf5bea254485d9ac4dc25947b5c18"><strong id="EN-US_TOPIC_0000001510522673__b962218129612">optimal</strong>: The list of candidate computing Node Groups consists of the Node Group where the operator's operation objects are located and the DNs in the Node Groups on which the current user has the COMPUTE permission.</li><li id="EN-US_TOPIC_0000001510522673__l23cd64e035524005929848d0127b3d8e"><strong id="EN-US_TOPIC_0000001510522673__b141595160612">query</strong>: The list of candidate computing Node Groups consists of the Node Group where the operator's operation objects are located and the DNs in the Node Groups where base tables involved in the query are located.</li><li id="EN-US_TOPIC_0000001510522673__li168897411428"><strong id="EN-US_TOPIC_0000001510522673__b21821241662">bind</strong>: If the current session user is a logical cluster user, the candidate computing Node Group is the Node Group of the logical cluster associated with the current user. If the session user is not a logical cluster user, the candidate computing Node Group selection rule is the same as that when this parameter is set to <strong id="EN-US_TOPIC_0000001510522673__b699811401962">query</strong>.</li><li id="EN-US_TOPIC_0000001510522673__li71490412910">Node Group name:<ul id="EN-US_TOPIC_0000001510522673__ul5251419201"><li id="EN-US_TOPIC_0000001510522673__li14884205891915">If <a href="#EN-US_TOPIC_0000001510522673__section1426622145210">enable_nodegroup_debug</a> is set to <strong id="EN-US_TOPIC_0000001510522673__b206472014719">off</strong>, the list of candidate computing Node Groups consists of the Node Group where the operator's operation objects are located and the specified Node Group.</li><li id="EN-US_TOPIC_0000001510522673__li1990917581195">If <a href="#EN-US_TOPIC_0000001510522673__section1426622145210">enable_nodegroup_debug</a> is set to <strong id="EN-US_TOPIC_0000001510522673__b1035181461520">on</strong>, the specified Node Group is used as the candidate Node Group.</li></ul>
</li></ul>
<p id="EN-US_TOPIC_0000001510522673__a97c28ae246e3464aa63de98c910603c4"><strong id="EN-US_TOPIC_0000001510522673__b842352706153219">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b842352706153224">bind</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__section1426622145210"><a name="EN-US_TOPIC_0000001510522673__section1426622145210"></a><a name="section1426622145210"></a><h4 class="sectiontitle">enable_nodegroup_debug</h4><p id="EN-US_TOPIC_0000001510522673__p1248710216535"><strong id="EN-US_TOPIC_0000001510522673__b94888220534">Parameter description</strong>: Specifies whether the optimizer assigns computing workloads to a specific Node Group when multiple Node Groups exist in an environment. The Node Group mechanism is now for internal use only. You do not need to set it.</p>
<p id="EN-US_TOPIC_0000001510522673__p8421114485619">This parameter takes effect only when <a href="#EN-US_TOPIC_0000001510522673__section746841514523">expected_computing_nodegroup</a> is set to a specific Node Group.</p>
<p id="EN-US_TOPIC_0000001510522673__p131469593317"><strong id="EN-US_TOPIC_0000001510522673__b19866151319127">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__p20491152165318"><strong id="EN-US_TOPIC_0000001510522673__en-us_topic_0059778346_en-us_topic_0058967673_b6625143011450_1">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001510522673__ul1449316295319"><li id="EN-US_TOPIC_0000001510522673__li12495182145315"><strong id="EN-US_TOPIC_0000001510522673__b842352706153524">on</strong> indicates that computing workloads are assigned to the Node Group specified by <strong id="EN-US_TOPIC_0000001510522673__b842352706153618">expected_computing_nodegroup</strong>.</li><li id="EN-US_TOPIC_0000001510522673__li1149710205315"><strong id="EN-US_TOPIC_0000001510522673__b1239936307154553">off</strong> indicates no Node Group is specified to compute.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__p849917295316"><strong id="EN-US_TOPIC_0000001510522673__b1091355087">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b365068210">off</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__section142331927115214"><h4 class="sectiontitle">stream_multiple</h4><p id="EN-US_TOPIC_0000001510522673__a823749263dcf480d87015cebb3d21907"><strong id="EN-US_TOPIC_0000001510522673__b842352706154610">Parameter description</strong>: Specifies the weight used for optimizer to calculate the final cost of stream operators.</p>
<p id="EN-US_TOPIC_0000001510522673__p76371053324">The base stream cost is multiplied by this weight to make the final cost.</p>
<p id="EN-US_TOPIC_0000001510522673__p9113615153214"><strong id="EN-US_TOPIC_0000001510522673__b740414151215">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__a3eb9ce875ece46a9b52c18cc8f2b7b59"><strong id="EN-US_TOPIC_0000001510522673__b842352706155342">Value range</strong>: a floating point number ranging from 0 to DBL_MAX</p>
<p id="EN-US_TOPIC_0000001510522673__aa92db8f81a9d44719aeeec06c0ec218c"><strong id="EN-US_TOPIC_0000001510522673__b66927520111326">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b842352706122628">1</strong></p>
<div class="notice" id="EN-US_TOPIC_0000001510522673__note4849184882913"><span class="noticetitle"><img src="public_sys-resources/notice_3.0-en-us.png"> </span><div class="noticebody"><p id="EN-US_TOPIC_0000001510522673__p9748916445">This parameter is applicable only to Redistribute and Broadcast streams.</p>
</div></div>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__section207996212178"><h4 class="sectiontitle">qrw_inlist2join_optmode</h4><p id="EN-US_TOPIC_0000001510522673__p07995213179"><strong id="EN-US_TOPIC_0000001510522673__b638072535319">Parameter description</strong>: Specifies whether enable inlist-to-join (inlist2join) query rewriting.</p>
<p id="EN-US_TOPIC_0000001510522673__p6802114273211"><strong id="EN-US_TOPIC_0000001510522673__b14209111421218">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__p18799221141716"><strong id="EN-US_TOPIC_0000001510522673__b1878112987">Value range</strong>: a string</p>
<ul id="EN-US_TOPIC_0000001510522673__ul826711518189"><li id="EN-US_TOPIC_0000001510522673__li142671651111819"><strong id="EN-US_TOPIC_0000001510522673__b193124191558">disable</strong>: inlist2join disabled</li><li id="EN-US_TOPIC_0000001510522673__li192673514184"><strong id="EN-US_TOPIC_0000001510522673__b583904415518">cost_base</strong>: cost-based inlist2join query rewriting</li><li id="EN-US_TOPIC_0000001510522673__li62672518185"><strong id="EN-US_TOPIC_0000001510522673__b13548179105610">rule_base</strong>: forcible rule-based inlist2join query rewriting</li><li id="EN-US_TOPIC_0000001510522673__li6267751141814">A positive integer: threshold of Inlist2join query rewriting. If the number of elements in the list is greater than the threshold, the rewriting is performed.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__p19799152117179"><strong id="EN-US_TOPIC_0000001510522673__b5750214">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b84235270617717">cost_base</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__section3354328409"><h4 class="sectiontitle">setop_optmode</h4><p id="EN-US_TOPIC_0000001510522673__p1535432144016"><strong id="EN-US_TOPIC_0000001510522673__b221658201116">Parameter description</strong>: Specifies whether to perform deduplication on the query branch statements of a set operation (<strong id="EN-US_TOPIC_0000001510522673__b591338112">UNION</strong>/<strong id="EN-US_TOPIC_0000001510522673__b209133181110">EXCEPT</strong>/<strong id="EN-US_TOPIC_0000001510522673__b1791433141110">INTERSECT</strong>) without the <strong id="EN-US_TOPIC_0000001510522673__b88026398122">ALL</strong> option. This parameter is supported by version 8.2.0 or later clusters.</p>
<p id="EN-US_TOPIC_0000001510522673__p103547284011"><strong id="EN-US_TOPIC_0000001510522673__b1095540125">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__p2354126408"><strong id="EN-US_TOPIC_0000001510522673__b03545214014">Value range</strong>: enumerated values</p>
<ul id="EN-US_TOPIC_0000001510522673__ul5354424405"><li id="EN-US_TOPIC_0000001510522673__li63545212409"><strong id="EN-US_TOPIC_0000001510522673__b170644910131">disable</strong>: The query branch does not perform deduplication.</li><li id="EN-US_TOPIC_0000001510522673__li13354529401"><strong id="EN-US_TOPIC_0000001510522673__b1136390101410">force</strong>: The query branch forcibly performs deduplication.</li><li id="EN-US_TOPIC_0000001510522673__li9354126404"><strong id="EN-US_TOPIC_0000001510522673__b166721614101417">cost</strong>: The optimizer compares the costs of query branches with and without deduplication, and choose the execution mode with lower costs.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__p143541721405">The default value is <strong id="EN-US_TOPIC_0000001510522673__b110132261342518">disable</strong>.</p>
<div class="notice" id="EN-US_TOPIC_0000001510522673__note470291474812"><span class="noticetitle"><img src="public_sys-resources/notice_3.0-en-us.png"> </span><div class="noticebody"><p id="EN-US_TOPIC_0000001510522673__p195781448162">This parameter takes effect only if the execution plan of a SQL statement meets the following conditions:</p>
<ul id="EN-US_TOPIC_0000001510522673__ul1358163443617"><li id="EN-US_TOPIC_0000001510522673__li13583344368">The <strong id="EN-US_TOPIC_0000001510522673__b64291416102712">UNION</strong>, <strong id="EN-US_TOPIC_0000001510522673__b8294161818277">EXCEPT</strong>, and <strong id="EN-US_TOPIC_0000001510522673__b11468919172711">INTERSECT</strong> operations in the SQL statement do not contain the <strong id="EN-US_TOPIC_0000001510522673__b179727206279">ALL</strong> option.</li><li id="EN-US_TOPIC_0000001510522673__li4840103710365">Data redistribution has been performed on the query branches where the set operation is to be performed.</li></ul>
</div></div>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__section1211182712176"><a name="EN-US_TOPIC_0000001510522673__section1211182712176"></a><a name="section1211182712176"></a><h4 class="sectiontitle">skew_option</h4><p id="EN-US_TOPIC_0000001510522673__p131156271171"><strong id="EN-US_TOPIC_0000001510522673__b6506181813572">Parameter description</strong>: Specifies whether an optimization policy is used</p>
<p id="EN-US_TOPIC_0000001510522673__p1841374916324"><strong id="EN-US_TOPIC_0000001510522673__b9378171441216">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__p411902711174"><strong id="EN-US_TOPIC_0000001510522673__b774600637">Value range</strong>: a string</p>
<ul id="EN-US_TOPIC_0000001510522673__ul9122142741716"><li id="EN-US_TOPIC_0000001510522673__li19123112714178"><strong id="EN-US_TOPIC_0000001510522673__b1680514483576">off</strong>: policy disabled</li><li id="EN-US_TOPIC_0000001510522673__li612772711711"><strong id="EN-US_TOPIC_0000001510522673__b683816522579">normal</strong>: radical policy. All possible skews are optimized.</li><li id="EN-US_TOPIC_0000001510522673__li5131142721714"><strong id="EN-US_TOPIC_0000001510522673__b380633010585">lazy</strong>: conservative policy. Uncertain skews are ignored.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__p12134102711710"><strong id="EN-US_TOPIC_0000001510522673__b71351827151719">Default value:</strong> <strong id="EN-US_TOPIC_0000001510522673__b1833214160599">normal</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__section6164935889"><h4 class="sectiontitle">prefer_hashjoin_path</h4><p id="EN-US_TOPIC_0000001510522673__p1716413351284"><strong id="EN-US_TOPIC_0000001510522673__b617017193389">Parameter description</strong>: whether to preferentially generate hashjoin paths so that other paths with high costs can be pre-pruned to shorten the overall plan generation time. This parameter is supported only by clusters of version 8.2.1 or later.</p>
<p id="EN-US_TOPIC_0000001510522673__p161640355816"><strong id="EN-US_TOPIC_0000001510522673__b1560833070">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__p31642035786"><strong id="EN-US_TOPIC_0000001510522673__b125025668">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001510522673__ul11648350811"><li id="EN-US_TOPIC_0000001510522673__li71642035984"><strong id="EN-US_TOPIC_0000001510522673__b1742920018394">off</strong>: disables the optimizations generated in advance in the hashjoin path.</li><li id="EN-US_TOPIC_0000001510522673__li816483515815"><strong id="EN-US_TOPIC_0000001510522673__b10784121316427">on</strong>: enables the optimizations generated in advance in the hashjoin path.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__p8164935388"><strong id="EN-US_TOPIC_0000001510522673__b1897928789">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b1259161264">on</strong></p>
</div>
<div class="section" id="EN-US_TOPIC_0000001510522673__section4105143712415"><h4 class="sectiontitle">enable_hashfilter_test</h4><p id="EN-US_TOPIC_0000001510522673__p121054376415"><strong id="EN-US_TOPIC_0000001510522673__b11477102764215">Parameter description</strong>: whether to add hash filters to columns for base table scan to check whether the results meet expectations. In addition, this parameter determines whether to check the DN accuracy when data is inserted (that is, whether the current data should be inserted into the current DN). This parameter is supported only by clusters of version 8.2.1.300 or later.</p>
<p id="EN-US_TOPIC_0000001510522673__p181057374412"><strong id="EN-US_TOPIC_0000001510522673__b1476087095">Type</strong>: USERSET</p>
<p id="EN-US_TOPIC_0000001510522673__p510519370419"><strong id="EN-US_TOPIC_0000001510522673__b847417016">Value range</strong>: Boolean</p>
<ul id="EN-US_TOPIC_0000001510522673__ul610511378418"><li id="EN-US_TOPIC_0000001510522673__li110503714419"><strong id="EN-US_TOPIC_0000001510522673__b2013103854512">off</strong> indicates that hash filters are not added to columns for base table scan, and the DN accuracy is not verified during data insertion.</li><li id="EN-US_TOPIC_0000001510522673__li15105133718411"><strong id="EN-US_TOPIC_0000001510522673__b364571018453">on</strong> indicates that hash filters are added to columns for base table scan, and the DN accuracy is verified during data insertion.</li></ul>
<p id="EN-US_TOPIC_0000001510522673__p91058370416"><strong id="EN-US_TOPIC_0000001510522673__b1382287073">Default value</strong>: <strong id="EN-US_TOPIC_0000001510522673__b527838002">on</strong></p>
<div class="notice" id="EN-US_TOPIC_0000001510522673__note1562771715119"><span class="noticetitle"><img src="public_sys-resources/notice_3.0-en-us.png"> </span><div class="noticebody"><ul id="EN-US_TOPIC_0000001510522673__ul05327451207"><li id="EN-US_TOPIC_0000001510522673__li55321945152011">This parameter is valid only for tables distributed in hash mode.</li><li id="EN-US_TOPIC_0000001510522673__li118117481201">If this parameter is set to <strong id="EN-US_TOPIC_0000001510522673__b32171497444">on</strong>, DN accuracy is verified during data insertion, affecting data insertion performance.</li></ul>
</div></div>
</div>
</div>
<div>
<div class="familylinks">
<div class="parentlink"><strong>Parent topic:</strong> <a href="dws_04_0908.html">Query Planning</a></div>
</div>
</div>