forked from docs/doc-exports
Lu, Huayi
a24ca60074
Reviewed-by: Hasko, Vladimir <vladimir.hasko@t-systems.com> Co-authored-by: Lu, Huayi <luhuayi@huawei.com> Co-committed-by: Lu, Huayi <luhuayi@huawei.com>
81 lines
19 KiB
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81 lines
19 KiB
HTML
<a name="EN-US_TOPIC_0000001145894627"></a><a name="EN-US_TOPIC_0000001145894627"></a>
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<h1 class="topictitle1">Cluster Transaction Parameters</h1>
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<div id="body8662426"><p id="EN-US_TOPIC_0000001145894627__en-us_topic_0059778361_p105914161197">This section describes the settings and value ranges of cluster transaction parameters.</p>
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<div class="section" id="EN-US_TOPIC_0000001145894627__sd9d0a139a3474dff81c16afbd8fca303"><h4 class="sectiontitle">transaction_isolation</h4><p id="EN-US_TOPIC_0000001145894627__a3aa0cf32ab594e0f8d294570595fa7b5"><strong id="EN-US_TOPIC_0000001145894627__b35889067">Parameter description</strong>: Specifies the isolation level of the current transaction.</p>
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<p id="EN-US_TOPIC_0000001145894627__p8226203042311"><strong id="EN-US_TOPIC_0000001145894627__b455234864714">Type</strong>: USERSET</p>
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<p id="EN-US_TOPIC_0000001145894627__ab4b08ba65613402ca13fdfd09580d982"><strong id="EN-US_TOPIC_0000001145894627__en-us_topic_0059778361_aa2861b35266d48acac63aff112fc5b1e">Value range</strong>:</p>
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<ul id="EN-US_TOPIC_0000001145894627__ul29345551841"><li id="EN-US_TOPIC_0000001145894627__li18934145519418"><strong id="EN-US_TOPIC_0000001145894627__b7742154463910">READ COMMITTED</strong>: Only committed data is read. This is the default.</li><li id="EN-US_TOPIC_0000001145894627__li15934155516411"><strong id="EN-US_TOPIC_0000001145894627__b12476306515">READ UNCOMMITTED</strong>: <span id="EN-US_TOPIC_0000001145894627__text114817025111">GaussDB(DWS)</span> does not support <strong id="EN-US_TOPIC_0000001145894627__b648280135119">READ UNCOMMITTED</strong>. If <strong id="EN-US_TOPIC_0000001145894627__b1348250195119">READ UNCOMMITTED</strong> is set, <strong id="EN-US_TOPIC_0000001145894627__b648214035114">READ COMMITTED</strong> is executed instead.</li><li id="EN-US_TOPIC_0000001145894627__li10935555244"><strong id="EN-US_TOPIC_0000001145894627__b1285610492390">REPEATABLE READ</strong>: Only the data committed before transaction start is read. Uncommitted data or data committed in other concurrent transactions cannot be read.</li><li id="EN-US_TOPIC_0000001145894627__li593511551545"><strong id="EN-US_TOPIC_0000001145894627__b1936417315513">SERIALIZABLE</strong>: <span id="EN-US_TOPIC_0000001145894627__text5364234515">GaussDB(DWS)</span> does not support <strong id="EN-US_TOPIC_0000001145894627__b12365113135120">SERIALIZABLE</strong>. If <strong id="EN-US_TOPIC_0000001145894627__b6365203125111">SERIALIZABLE</strong> is set, <strong id="EN-US_TOPIC_0000001145894627__b1136523165119">REPEATABLE READ</strong> is executed instead.</li></ul>
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<p id="EN-US_TOPIC_0000001145894627__aa41331776092480a9260b8dc77b4ca96"><strong id="EN-US_TOPIC_0000001145894627__b479916411513">Default value</strong>: <strong id="EN-US_TOPIC_0000001145894627__b380074105112">READ COMMITTED</strong></p>
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</div>
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<div class="section" id="EN-US_TOPIC_0000001145894627__s5b210d8773694747a97b5762787d25aa"><h4 class="sectiontitle">transaction_read_only</h4><p id="EN-US_TOPIC_0000001145894627__abcabb10e66a844b0ad124c3f6741b6fe"><strong id="EN-US_TOPIC_0000001145894627__en-us_topic_0059778361_en-us_topic_0058967582_b322665192930">Parameter description</strong>: Specifies that the current transaction is a read-only transaction.</p>
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<p id="EN-US_TOPIC_0000001145894627__p5131749173010"><strong id="EN-US_TOPIC_0000001145894627__b4130249104714">Type</strong>: USERSET</p>
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<p id="EN-US_TOPIC_0000001145894627__ac97a1e9552374e1db93d64b2b6f325df"><strong id="EN-US_TOPIC_0000001145894627__en-us_topic_0059778361_a4df0f3e6fb4a4993bd151746fc29b615">Value range</strong>: Boolean</p>
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<ul id="EN-US_TOPIC_0000001145894627__u85dc5fab8eeb4314a4f8a73004d05c04"><li id="EN-US_TOPIC_0000001145894627__l5ff982d837af4a508b89b5548f5c2e0f"><strong id="EN-US_TOPIC_0000001145894627__b842352706135927">on</strong> indicates that the current transaction is a read-only transaction.</li><li id="EN-US_TOPIC_0000001145894627__l34bf0273a8fc4073a891876d32b7ca9e"><strong id="EN-US_TOPIC_0000001145894627__b262131805135937">off</strong> indicates that the current transaction can be a read/write transaction.</li></ul>
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<p id="EN-US_TOPIC_0000001145894627__a949cf344300947418214e147ad90a007"><strong id="EN-US_TOPIC_0000001145894627__b727904018912">Default value</strong>: <strong id="EN-US_TOPIC_0000001145894627__b4654195919916">off</strong> for CNs and <strong id="EN-US_TOPIC_0000001145894627__b16773291018">on</strong> for DNs</p>
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</div>
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<div class="section" id="EN-US_TOPIC_0000001145894627__s63b833ea501244038bfa5d6466719514"><h4 class="sectiontitle">xc_maintenance_mode</h4><p id="EN-US_TOPIC_0000001145894627__a6b74b43a38ba41f8b8f291a25c273767"><strong id="EN-US_TOPIC_0000001145894627__b8585964515">Parameter description</strong>: Specifies whether the system is in maintenance mode.</p>
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<p id="EN-US_TOPIC_0000001145894627__p105394519166"><strong id="EN-US_TOPIC_0000001145894627__b2285154712163">Type</strong>: SUSET</p>
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<p id="EN-US_TOPIC_0000001145894627__a8dd1424a7ab14e00a7793bcaf4297ba2"><strong id="EN-US_TOPIC_0000001145894627__b1028661575117">Value range</strong>: Boolean</p>
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<ul id="EN-US_TOPIC_0000001145894627__u5f312998310e41a89a1ad3def442a72a"><li id="EN-US_TOPIC_0000001145894627__l0634ecb7a7164c509f693c21f9d209bd"><strong id="EN-US_TOPIC_0000001145894627__b771581645120">on</strong> indicates that maintenance mode is enabled.</li><li id="EN-US_TOPIC_0000001145894627__l27e1b0a780f54873a4a1b5074c9a56f9"><strong id="EN-US_TOPIC_0000001145894627__b9164121845113">off</strong> indicates that the maintenance mode is disabled.</li></ul>
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<p id="EN-US_TOPIC_0000001145894627__a223505c9e8a04530b8a56b3d7003eb59"><strong id="EN-US_TOPIC_0000001145894627__b55233292105553">Default value</strong>: <strong id="EN-US_TOPIC_0000001145894627__b842352706172155">off</strong></p>
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<div class="notice" id="EN-US_TOPIC_0000001145894627__naf35617accbd4929904bc019b87774ec"><span class="noticetitle"><img src="public_sys-resources/notice_3.0-en-us.png"> </span><div class="noticebody"><p id="EN-US_TOPIC_0000001145894627__af187cf68aade4c78bb7f8b8d8152c7e6">Enable the maintenance mode with caution to avoid cluster data inconsistencies.</p>
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</div></div>
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</div>
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<div class="section" id="EN-US_TOPIC_0000001145894627__se7223079970b4a10b569ada583d6f3d9"><h4 class="sectiontitle">allow_concurrent_tuple_update</h4><p id="EN-US_TOPIC_0000001145894627__adf29a5cb72784a39a65511ccedbd7234"><strong id="EN-US_TOPIC_0000001145894627__en-us_topic_0059778361_aa9f6a14a274e43ae8f83b10d7f3b8d22">Parameter description</strong>: Specifies whether to allow concurrent update.</p>
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<p id="EN-US_TOPIC_0000001145894627__p79901258113011"><strong id="EN-US_TOPIC_0000001145894627__b16493849134719">Type</strong>: USERSET</p>
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<p id="EN-US_TOPIC_0000001145894627__a34b42a18cf3e483c810a382ecc17d516"><strong id="EN-US_TOPIC_0000001145894627__b240091920511">Value range</strong>: Boolean</p>
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<ul id="EN-US_TOPIC_0000001145894627__ud5f3744ec40e4941b67635417d7977df"><li id="EN-US_TOPIC_0000001145894627__lf2cd7aa63c834ee19a8c880a03b2c33c"><strong id="EN-US_TOPIC_0000001145894627__b547922910514">on</strong> indicates it is enabled.</li><li id="EN-US_TOPIC_0000001145894627__l91a00a3607bd410eb3eacdda6dc89fb7"><strong id="EN-US_TOPIC_0000001145894627__b5564203818516">off</strong> indicates it is disabled.</li></ul>
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<p id="EN-US_TOPIC_0000001145894627__a008a0521c7b14fac96e6f64d042288ad"><strong id="EN-US_TOPIC_0000001145894627__b337814198113">Default value</strong>: <strong id="EN-US_TOPIC_0000001145894627__b18386219413">on</strong></p>
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</div>
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<div class="section" id="EN-US_TOPIC_0000001145894627__s07f04c9e09dd49f99d806c6d1b222730"><h4 class="sectiontitle">gtm_backup_barrier</h4><p id="EN-US_TOPIC_0000001145894627__ad50d6ecfaa9d4e3da30b22737ab58f2a"><strong id="EN-US_TOPIC_0000001145894627__en-us_topic_0059778361_en-us_topic_0058967582_b767844611582">Parameter description</strong>: Specifies whether to create a restoration point for the GTM starting point.</p>
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<p id="EN-US_TOPIC_0000001145894627__a06805fcf12a446f0be207f4f94b471d0"><strong id="EN-US_TOPIC_0000001145894627__b8591232102815">Type</strong>: SUSET</p>
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<p id="EN-US_TOPIC_0000001145894627__a5a4ebd449cc44813b10995d7a9849f1d"><strong id="EN-US_TOPIC_0000001145894627__en-us_topic_0059778361_ad5cccb767b8a44de96027a65c28eae04">Value range</strong>: Boolean</p>
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<ul id="EN-US_TOPIC_0000001145894627__u0c3671dd188646878bddcef77fe00a1c"><li id="EN-US_TOPIC_0000001145894627__l654a5e6de0e84d8f851d385dd4be92dd"><strong id="EN-US_TOPIC_0000001145894627__b84235270614160">on</strong> indicates that a restoration point will be created for the GTM starting point.</li><li id="EN-US_TOPIC_0000001145894627__l5fb3b33f60ac45ffa35ae626f00af4d2"><strong id="EN-US_TOPIC_0000001145894627__b4330817114166">off</strong> indicates that a restoration point will not be created for the GTM starting point.</li></ul>
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<p id="EN-US_TOPIC_0000001145894627__ab993733625ce4e3a89b398161d4570b5"><strong id="EN-US_TOPIC_0000001145894627__b1093440724">Default value</strong>: <strong id="EN-US_TOPIC_0000001145894627__b742229853">off</strong></p>
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</div>
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<div class="section" id="EN-US_TOPIC_0000001145894627__s2b18232f556043c898407e02edfdef1b"><h4 class="sectiontitle">gtm_conn_check_interval</h4><p id="EN-US_TOPIC_0000001145894627__a453fae8573374bb9872b03f5cd024b8c"><strong id="EN-US_TOPIC_0000001145894627__en-us_topic_0059778361_ab92dfadc151e46d1922a24ebf6f15641">Parameter description</strong>: Sets the CN to check whether the connection between the local thread and the primary GTM is normal.</p>
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<p id="EN-US_TOPIC_0000001145894627__p10945314640"><strong id="EN-US_TOPIC_0000001145894627__b84367335283">Type</strong>: SIGHUP</p>
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<p id="EN-US_TOPIC_0000001145894627__a858f586ddd5349228d0dfe6e988a3577"><strong id="EN-US_TOPIC_0000001145894627__en-us_topic_0059778361_af21f52970486449e9e227ae87d38b721">Value range</strong>: an integer ranging from 0 to INT_MAX/1000. The unit is second.</p>
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<p id="EN-US_TOPIC_0000001145894627__a51adf803b81741c0afd5cdbdcca1e02e"><strong id="EN-US_TOPIC_0000001145894627__b586515861640">Default value</strong>: <strong id="EN-US_TOPIC_0000001145894627__b842352706165728">10s</strong></p>
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</div>
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<div class="section" id="EN-US_TOPIC_0000001145894627__s03d3940b5f7549e3a3e7c32ab36bf3d7"><h4 class="sectiontitle">transaction_deferrable</h4><p id="EN-US_TOPIC_0000001145894627__a5d2d66ff9139422cb67b48e3abc96620"><strong id="EN-US_TOPIC_0000001145894627__en-us_topic_0059778361_a90a94ff5e6d24dc280359d489253d598">Parameter description</strong>: Specifies whether to delay the execution of a read-only serial transaction without incurring an execution failure. Assume this parameter is set to <span class="parmvalue" id="EN-US_TOPIC_0000001145894627__parmvalue20382124413512"><b>on</b></span>. When the server detects that the tuples read by a read-only transaction are being modified by other transactions, it delays the execution of the read-only transaction until the other transactions finish modifying the tuples. Currently, this parameter is not used in <span id="EN-US_TOPIC_0000001145894627__text1262829036">GaussDB(DWS)</span>. Similar to this parameter, the <a href="dws_04_0925.html#EN-US_TOPIC_0000001145894759__s05ef9312d74143928830d7d459cdc63a">default_transaction_deferrable</a> parameter is used to specify whether to allow delayed execution of a transaction.</p>
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<p id="EN-US_TOPIC_0000001145894627__p1569631414312"><strong id="EN-US_TOPIC_0000001145894627__b1751349204715">Type</strong>: USERSET</p>
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<p id="EN-US_TOPIC_0000001145894627__a056768eae8e644f28561178ab3729a3f"><strong id="EN-US_TOPIC_0000001145894627__en-us_topic_0059778361_ac29187570a8f43cf841edf4e3238409c">Value range</strong>: Boolean</p>
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<ul id="EN-US_TOPIC_0000001145894627__uf3003cf8c9e040c5a26731db10c52c14"><li id="EN-US_TOPIC_0000001145894627__ld010140e463444bf8c9d746c78d25ebf"><strong id="EN-US_TOPIC_0000001145894627__b842352706142640">on</strong> indicates that the execution of a read-only serial transaction can be delayed.</li><li id="EN-US_TOPIC_0000001145894627__l62bc5fd4fbb94bc88b0d019c7490ff4d"><strong id="EN-US_TOPIC_0000001145894627__b973132058142723">off</strong> indicates that the execution of a read-only serial transaction cannot be delayed.</li></ul>
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<p id="EN-US_TOPIC_0000001145894627__a04472cbfc2304b0f97382008105c5ddd"><strong id="EN-US_TOPIC_0000001145894627__b57133721">Default value</strong>: <strong id="EN-US_TOPIC_0000001145894627__b363848775">off</strong></p>
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</div>
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<div class="section" id="EN-US_TOPIC_0000001145894627__s9286953201d046bc9731dd5231351a0b"><h4 class="sectiontitle">enforce_two_phase_commit</h4><p id="EN-US_TOPIC_0000001145894627__a5da4529f0bad4b78b7318f88e1df2558"><strong id="EN-US_TOPIC_0000001145894627__b1378314536112">Parameter description</strong>: This parameter is reserved for compatibility with earlier versions. This parameter is invalid in the current version.</p>
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</div>
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<div class="section" id="EN-US_TOPIC_0000001145894627__s5ca6923d335f477e892a8d03a295b7c1"><h4 class="sectiontitle">enable_show_any_tuples</h4><p id="EN-US_TOPIC_0000001145894627__ab3597abe43794d1591452b12e311fd13"><strong id="EN-US_TOPIC_0000001145894627__en-us_topic_0059778361_af31d26307b4542e6a47eb50b9fe44166">Parameter description</strong>: This parameter is available only in a read-only transaction and is used for analysis. When this parameter is set to <span class="parmvalue" id="EN-US_TOPIC_0000001145894627__parmvalue555125744145417"><b>on/true</b></span>, all versions of tuples in the table are displayed.</p>
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<p id="EN-US_TOPIC_0000001145894627__p12968102333113"><strong id="EN-US_TOPIC_0000001145894627__b69245494471">Type</strong>: USERSET</p>
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<p id="EN-US_TOPIC_0000001145894627__a8d190b57a3864bd3b10eb4f06af98c5c"><strong id="EN-US_TOPIC_0000001145894627__en-us_topic_0059778361_af42e3dda855140f0b4586b97281083ec">Value range</strong>: Boolean</p>
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<ul id="EN-US_TOPIC_0000001145894627__u7270295d899747898cece372408b058f"><li id="EN-US_TOPIC_0000001145894627__l1115ab2d646b41eb8890f0c9cf4c0651"><strong id="EN-US_TOPIC_0000001145894627__b842352706143110">on/true</strong> indicates that all versions of tuples in the table are displayed.</li><li id="EN-US_TOPIC_0000001145894627__lef793e587d6a4874869a5151e7d52504"><strong id="EN-US_TOPIC_0000001145894627__b143191698414555">off/false</strong> indicates that no versions of tuples in the table are displayed.</li></ul>
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<p id="EN-US_TOPIC_0000001145894627__a474e2f70eeb145cfbb1213c959787c4a"><strong id="EN-US_TOPIC_0000001145894627__b2119890472">Default value</strong>: <strong id="EN-US_TOPIC_0000001145894627__b1352600018">off</strong></p>
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</div>
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<div class="section" id="EN-US_TOPIC_0000001145894627__s23bdab2e9a9c4cb99c4f111930d178fd"><h4 class="sectiontitle">gtm_connect_retries</h4><p id="EN-US_TOPIC_0000001145894627__a7da176b453854452953985d85b2914bd"><strong id="EN-US_TOPIC_0000001145894627__en-us_topic_0059778361_a04d5d0435ee545acab9fab9aa8252dc0">Parameter description</strong>: Specifies the number of GTM reconnection attempts.</p>
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<p id="EN-US_TOPIC_0000001145894627__p6968195733216"><strong id="EN-US_TOPIC_0000001145894627__b115266523474">Type</strong>: SIGHUP</p>
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<p id="EN-US_TOPIC_0000001145894627__a47c636ced29a40408ba54f2b301108fd"><strong id="EN-US_TOPIC_0000001145894627__en-us_topic_0059778361_ae44b78fcb17441c0a2f2015972dfeac2">Value range</strong>: an integer ranging from 1 to 2147483647.</p>
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<p id="EN-US_TOPIC_0000001145894627__ae2bd7ec2de7046a0bf8ab93335c02213"><strong id="EN-US_TOPIC_0000001145894627__b31155792113852">Default value</strong>: <strong id="EN-US_TOPIC_0000001145894627__b842352706165012">30</strong></p>
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</div>
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<div class="section" id="EN-US_TOPIC_0000001145894627__sfe673b480cf6470e9e35638c40d8a4d6"><h4 class="sectiontitle">enable_redistribute</h4><p id="EN-US_TOPIC_0000001145894627__ac3b08162d8b94f288660e29a923f0f97"><strong id="EN-US_TOPIC_0000001145894627__en-us_topic_0059778361_b4059173510743">Parameter description</strong>: Specifies whether unmatched nodes are redistributed.</p>
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<p id="EN-US_TOPIC_0000001145894627__p1443581517326"><strong id="EN-US_TOPIC_0000001145894627__b136341053114717">Type</strong>: SUSET</p>
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<p id="EN-US_TOPIC_0000001145894627__aad6076370f25464c92405e49f84f8d2f"><strong id="EN-US_TOPIC_0000001145894627__en-us_topic_0059778361_b4731132610356">Value range</strong>: Boolean</p>
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<ul id="EN-US_TOPIC_0000001145894627__ucd38e4d73af14a94849992598b02f644"><li id="EN-US_TOPIC_0000001145894627__l33268466996345ecb31f33da7de59fc0"><strong id="EN-US_TOPIC_0000001145894627__b842352706113617">on</strong> indicates that unmatched nodes are redistributed.</li><li id="EN-US_TOPIC_0000001145894627__l7c763ea0ae7c4df681df938dff78ea06"><strong id="EN-US_TOPIC_0000001145894627__en-us_topic_0059778361_b710916210434">off</strong> indicates that unmatched nodes are not redistributed.</li></ul>
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<p id="EN-US_TOPIC_0000001145894627__a776d641d10a34625a33b0d361a124a96"><strong id="EN-US_TOPIC_0000001145894627__b323759270">Default value</strong>: <strong id="EN-US_TOPIC_0000001145894627__b1888366050">off</strong></p>
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</div>
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<div class="section" id="EN-US_TOPIC_0000001145894627__section1080710724310"><h4 class="sectiontitle">enable_gtm_free</h4><p id="EN-US_TOPIC_0000001145894627__p187310167421"><strong id="EN-US_TOPIC_0000001145894627__b18318755183012">Parameter description</strong>: Specifies whether the GTM-FREE mode is enabled. In large concurrency scenarios, the snapshots delivered by the GTM increase in number and size. The network between the GTM and the CN becomes the performance bottleneck. The GTM-FREE mode is used to eliminate the bottleneck. In this mode, the CN communicates with DNs instead of the GTM. The CN sends queries to each DN, which locally generates snapshots and xids, ensuring external write consistency but not external read consistency.</p>
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<p id="EN-US_TOPIC_0000001145894627__p9808197124319">You are not advised to set this parameter to <strong id="EN-US_TOPIC_0000001145894627__b1326434263818">on</strong> in OLTP or OLAP scenarios where strong read consistency is required. This parameter is invalid for <span id="EN-US_TOPIC_0000001145894627__text692451183">GaussDB(DWS)</span>.</p>
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<p id="EN-US_TOPIC_0000001145894627__p6690114213311"><strong id="EN-US_TOPIC_0000001145894627__b1557525615474">Type</strong>: SUSET</p>
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<p id="EN-US_TOPIC_0000001145894627__p781187164316"><strong id="EN-US_TOPIC_0000001145894627__b121158803">Value range</strong>: Boolean</p>
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<ul id="EN-US_TOPIC_0000001145894627__ul1813187114314"><li id="EN-US_TOPIC_0000001145894627__li981414711437"><strong id="EN-US_TOPIC_0000001145894627__b2054811433317">on</strong> indicates that the GTM-FREE mode is enabled and the cluster ensures eventual read consistency.</li><li id="EN-US_TOPIC_0000001145894627__li18815187144313"><strong id="EN-US_TOPIC_0000001145894627__b2903044173511">off</strong> indicates that the GTM-FREE mode is disabled.</li></ul>
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<p id="EN-US_TOPIC_0000001145894627__p20817177430"><strong id="EN-US_TOPIC_0000001145894627__b1854493907">Default value</strong>: <strong id="EN-US_TOPIC_0000001145894627__b1615305255">off</strong></p>
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<div class="parentlink"><strong>Parent topic:</strong> <a href="dws_04_0883.html">GUC Parameters</a></div>
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