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Hasko, Vladimir
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Reviewed-by: Wagner, Fabian <fabian.wagner@t-systems.com> Co-authored-by: Hasko, Vladimir <vladimir.hasko@t-systems.com> Co-committed-by: Hasko, Vladimir <vladimir.hasko@t-systems.com>
231 lines
23 KiB
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231 lines
23 KiB
HTML
<a name="ddm_03_0058"></a><a name="ddm_03_0058"></a>
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<h1 class="topictitle1">Modifying Parameters of a DDM Instance</h1>
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<div id="body1599014692106"><div class="section" id="ddm_03_0058__section1043419141576"><h4 class="sectiontitle">Scenarios</h4><p id="ddm_03_0058__p19195354377">Configure parameters of a DDM instance based on your needs to keep the instance running well.</p>
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</div>
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<div class="section" id="ddm_03_0058__section12394201812715"><h4 class="sectiontitle">Prerequisites</h4><p id="ddm_03_0058__p4684172171010">There is a DDM instance available and running normally.</p>
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</div>
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<div class="section" id="ddm_03_0058__section207314221578"><h4 class="sectiontitle">Procedure</h4><ol id="ddm_03_0058__ol0491151518162"><li id="ddm_03_0058__li06962345314"><span>Log in to the DDM console.</span></li><li id="ddm_03_0058__li77052375313"><span>In the navigation pane, choose <strong id="ddm_03_0058__b19182121131819">Instances</strong>.</span></li><li id="ddm_03_0058__li18387211659"><span>In the instance list, locate the DDM instance whose parameters you want to configure and click its name.</span></li><li id="ddm_03_0058__li2068254981610"><span>In the left pane, click <strong id="ddm_03_0058__b99144763519">Parameters</strong> and modify parameter values as needed.</span><p>
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<div class="tablenoborder"><table cellpadding="4" cellspacing="0" summary="" id="ddm_03_0058__table858192918336" frame="border" border="1" rules="all"><caption><b>Table 1 </b>Parameters of a DDM instance</caption><thead align="left"><tr id="ddm_03_0058__row115092973312"><th align="left" class="cellrowborder" valign="top" width="25%" id="mcps1.3.3.2.4.2.1.2.5.1.1"><p id="ddm_03_0058__p95016294338"><strong id="ddm_03_0058__b1430411619191">Parameter</strong></p>
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</th>
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<th align="left" class="cellrowborder" valign="top" width="25%" id="mcps1.3.3.2.4.2.1.2.5.1.2"><p id="ddm_03_0058__p1050192913317"><strong id="ddm_03_0058__b1968818437195">Description</strong></p>
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</th>
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<th align="left" class="cellrowborder" valign="top" width="25%" id="mcps1.3.3.2.4.2.1.2.5.1.3"><p id="ddm_03_0058__p956433116452"><strong id="ddm_03_0058__b9314432122612">Value Range</strong></p>
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</th>
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<th align="left" class="cellrowborder" valign="top" width="25%" id="mcps1.3.3.2.4.2.1.2.5.1.4"><p id="ddm_03_0058__p1750162912336"><strong id="ddm_03_0058__b312602241917">Default Value</strong></p>
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</th>
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</tr>
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</thead>
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<tbody><tr id="ddm_03_0058__row165162973320"><td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.1 "><p id="ddm_03_0058__p155032916332">bind_table</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.2 "><p id="ddm_03_0058__p155113290339">Data association among multiple sharded tables. The optimizer processes JOIN operations at the MySQL layer based on these associations. For details about parameter examples, see the description below the table.</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.3 "><p id="ddm_03_0058__p1564193194515">The value should be in format <strong id="ddm_03_0058__b108936299274">[{<table1>.<column1>,<table2>.<column2>},{<table1>.<column2>,<table3>.<column1>},...]</strong>. <em id="ddm_03_0058__i1689332911274"><table1>.<column1>,<table2>.<column2></em> indicates a table name.column name pair, and the value may contain multiple pairs.</p>
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<p id="ddm_03_0058__p17564103117454">The version should be:</p>
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<p id="ddm_03_0058__p656403114520">DDM 2.3.2.7 or later.</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.4 "><p id="ddm_03_0058__p15172911339">-</p>
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</td>
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</tr>
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<tr id="ddm_03_0058__row17403912132614"><td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.1 "><p id="ddm_03_0058__p15403141242615">character_set_server</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.2 "><p id="ddm_03_0058__p74031912182610">DDM server's character set. To store emoticons, set both this parameter and the character set on RDS to <strong id="ddm_03_0058__b8731559135211">utf8mb4</strong>.</p>
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<p id="ddm_03_0058__p18967144511510">For a DDM instance 3.0.9 or later, you can execute <strong id="ddm_03_0058__b138611814315">show variables like '%char%'</strong> to query its character set. You will find that <strong id="ddm_03_0058__b77812059617">character_set_client</strong>, <strong id="ddm_03_0058__b15411148610">character_set_results</strong>, and <strong id="ddm_03_0058__b131521269617">character_set_connection</strong> in the command output all have a fixed value, <strong id="ddm_03_0058__b97167431365">utf8mb4</strong>.</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.3 "><p id="ddm_03_0058__p35651931104514">gbk, utf8, utf8mb4</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.4 "><p id="ddm_03_0058__p440301220267">utf8mb4</p>
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</td>
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</tr>
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<tr id="ddm_03_0058__row1231535118262"><td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.1 "><p id="ddm_03_0058__p2315165162613">collation_server</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.2 "><p id="ddm_03_0058__p2316115113266">Collation on the DDM server.</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.3 "><p id="ddm_03_0058__p55651331194514">utf8mb4_unicode_ci, utf8mb4_bin, utf8mb4_general_ci</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.4 "><p id="ddm_03_0058__p19315651132618">utf8mb4_unicode_ci</p>
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</td>
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</tr>
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<tr id="ddm_03_0058__row789553518274"><td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.1 "><p id="ddm_03_0058__p148951535132717">concurrent_execution_level</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.2 "><p id="ddm_03_0058__p9895113514272">Concurrency level of scanning table shards in a logical table. <strong id="ddm_03_0058__b779793735313">DATA_NODE</strong>: indicates that database shards are scanned in parallel and table shards in each database shard are scanned in serial. <strong id="ddm_03_0058__b19798123765311">RDS_INSTANCE</strong>: indicates that RDS instances are scanned in parallel and shards in each instance are scanned in serial. <strong id="ddm_03_0058__b16798133710538">PHY_TABLE</strong>: indicates that all table shards are scanned in parallel.</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.3 "><p id="ddm_03_0058__p956533112453">RDS_INSTANCE, DATA_NODE, PHY_TABLE</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.4 "><p id="ddm_03_0058__p11895435192713">DATA_NODE</p>
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</td>
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</tr>
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<tr id="ddm_03_0058__row2021225916295"><td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.1 "><p id="ddm_03_0058__p62122590294">connection_idle_timeout</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.2 "><p id="ddm_03_0058__p7212195922913">Number of seconds the server waits for activity on a connection before closing it. The default value is <strong id="ddm_03_0058__b1473951065413">28800</strong>, indicating that the server waits for 28,800 seconds before closing a connection.</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.3 "><p id="ddm_03_0058__p1056523117452">60–86400</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.4 "><p id="ddm_03_0058__p112125599299">28800</p>
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</td>
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</tr>
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<tr id="ddm_03_0058__row1235492023220"><td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.1 "><p id="ddm_03_0058__p23551720123215">contains_shard_key</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.2 "><p id="ddm_03_0058__p93551720133220">Whether the SELECT, UPDATE, and DELETE statements must contain sharding keys in filter conditions.</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.3 "><p id="ddm_03_0058__p65653316457">OFF or ON</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.4 "><p id="ddm_03_0058__p635572012324">OFF</p>
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</td>
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</tr>
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<tr id="ddm_03_0058__row44271139125920"><td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.1 "><p id="ddm_03_0058__p24283396599">ddl_precheck_mdl_threshold_time</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.2 "><p id="ddm_03_0058__p14428143975915">Threshold of the MDL duration in DDL pre-check. The unit is second. The default value is <strong id="ddm_03_0058__b112864271575">120</strong>.</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.3 "><p id="ddm_03_0058__p1256573118458">1–3600</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.4 "><p id="ddm_03_0058__p74288391592">120</p>
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</td>
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</tr>
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<tr id="ddm_03_0058__row14805145814119"><td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.1 "><p id="ddm_03_0058__p1041910827">enable_table_recycle</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.2 "><p id="ddm_03_0058__p64201701123"><strong id="ddm_03_0058__b17372103975913">ON</strong>: indicates that the table recycle bin is enabled.</p>
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<p id="ddm_03_0058__p16420301322"><strong id="ddm_03_0058__b8151411401">OFF</strong>: indicates that the table recycle bin is disabled.</p>
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<p id="ddm_03_0058__p17869125918282">After the table recycle bin is enabled, deleted tables are moved to the recycle bin and can be recovered by running the RESTORE command within seven days.</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.3 "><p id="ddm_03_0058__p15657313459">OFF or ON</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.4 "><p id="ddm_03_0058__p84203010212">OFF</p>
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</td>
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</tr>
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<tr id="ddm_03_0058__row17447451514"><td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.1 "><p id="ddm_03_0058__p14471650513">long_query_time</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.2 "><p id="ddm_03_0058__p17447851454">Minimum duration of a query to be logged as slow, in seconds. The default value is <strong id="ddm_03_0058__b1620233815563">1</strong>, indicating that the query is considered as a slow query if its execution duration is greater than or equal to 1 second.</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.3 "><p id="ddm_03_0058__p1256543113451">0.01–10</p>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.4 "><p id="ddm_03_0058__p74471551957">1</p>
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</td>
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</tr>
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<tr id="ddm_03_0058__row3378195118619"><td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.1 "><p id="ddm_03_0058__p163781551369">max_allowed_packet</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.2 "><p id="ddm_03_0058__p437912510619">Maximum size of one packet or any generated intermediate string. The packet message buffer is initialized to <strong id="ddm_03_0058__b155562507567">net_buffer_length</strong> bytes, but can grow up to <strong id="ddm_03_0058__b14557185014563">max_allowed_packet</strong> bytes when needed. This value is small by default, to catch large (and possibly incorrect) packets. The value must be a multiple of <strong id="ddm_03_0058__b3810115615610">1024</strong>.</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.3 "><p id="ddm_03_0058__p17565173115451">1024–1073741824</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.4 "><p id="ddm_03_0058__p193781451362">1073741824</p>
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</td>
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</tr>
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<tr id="ddm_03_0058__row10606124616716"><td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.1 "><p id="ddm_03_0058__p136071146675">max_backend_connections</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.2 "><p id="ddm_03_0058__p14811951104218">Maximum of concurrent client connections allowed per DDM instance.</p>
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<p id="ddm_03_0058__p5594184010431">The default value is <strong id="ddm_03_0058__b161211934133613">0</strong>.</p>
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<p id="ddm_03_0058__p32791447104317">Actual value: (Maximum connections of RDS - 20)/DDM nodes</p>
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<p id="ddm_03_0058__p1760764616719">This parameter does not take effect only after maximum connections are set on RDS.</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.3 "><p id="ddm_03_0058__p11565153144510">0–10000000</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.4 "><p id="ddm_03_0058__p19607646476">0</p>
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</td>
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</tr>
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<tr id="ddm_03_0058__row05210293335"><td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.1 "><p id="ddm_03_0058__p1551202983317">max_connections</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.2 "><p id="ddm_03_0058__p155122917333">Minimum concurrent connections from a DDM instance node to the client.</p>
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<p id="ddm_03_0058__p175132913332">This value depends on specifications and processing capabilities of the target data node. Too many connections may cause connection waiting, affecting performance. The consumption of DDM connections varies with the number of shards and SQL design.</p>
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<p id="ddm_03_0058__p17521429183319">For example, If a SQL statement contains a sharding key, each DDM connection consumes one data node connection. If the SQL statement contains no sharding keys and the number of shards is N, N data node connections are consumed.</p>
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<p id="ddm_03_0058__p165232983315">If SQL design is appropriate and processing capabilities of DDM and its data nodes are good enough, you can set this parameter to a value slightly smaller than the product of backend data nodes x maximum connections supported by each data node.</p>
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<p id="ddm_03_0058__p19521829143310">Carry out pressure tests on your services and then select a proper value.</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.3 "><p id="ddm_03_0058__p20565173117454">10–40000</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.4 "><p id="ddm_03_0058__p1151429143310">20000</p>
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</td>
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</tr>
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<tr id="ddm_03_0058__row101130191918"><td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.1 "><p id="ddm_03_0058__p61131719392">min_backend_connections</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.2 "><p id="ddm_03_0058__p10113151911910">Minimum concurrent connections from a DDM node to an RDS instance. The default value is <strong id="ddm_03_0058__b158465619573">10</strong>.</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.3 "><p id="ddm_03_0058__p1156513311459">0–10000000</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.4 "><p id="ddm_03_0058__p111312196916">10</p>
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</td>
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</tr>
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<tr id="ddm_03_0058__row148332012138"><td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.1 "><p id="ddm_03_0058__p1483112061313">seconds_behind_master</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.2 "><p id="ddm_03_0058__p383112091317">Threshold in seconds of the replication lag between a primary RDS instance to its read replica. The default value is <strong id="ddm_03_0058__b998551355716">30</strong>, indicating that the time for data replication between the primary RDS instance and its read replicas cannot exceed 30 seconds. If the time exceeds 30 seconds, the data read requests are no longer forwarded to the read replicas.</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.3 "><p id="ddm_03_0058__p1256513115455">0–7200</p>
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</td>
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<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.4 "><p id="ddm_03_0058__p1183020151320">30</p>
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</td>
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</tr>
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<tr id="ddm_03_0058__row029782310140"><td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.1 "><p id="ddm_03_0058__p4430453181418">sql_execute_timeout</p>
|
||
</td>
|
||
<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.2 "><p id="ddm_03_0058__p1843365371417">Number of seconds to wait for a SQL statement to execute before it times out. The default value is <strong id="ddm_03_0058__b2861162310571">28800</strong>, indicating that the SQL statement times out if its execution time is greater than or equal to 28800 seconds.</p>
|
||
<p id="ddm_03_0058__p369218424142">For data nodes, ensure that <strong id="ddm_03_0058__b48294402428">net_write_timeout</strong> has a greater value than <strong id="ddm_03_0058__b17651185916427">sql_execute_timeout</strong>.</p>
|
||
</td>
|
||
<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.3 "><p id="ddm_03_0058__p19565153154517">100–28800</p>
|
||
</td>
|
||
<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.4 "><p id="ddm_03_0058__p128719137412">28800</p>
|
||
</td>
|
||
</tr>
|
||
<tr id="ddm_03_0058__row1396253951417"><td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.1 "><p id="ddm_03_0058__p4430053161418">temp_table_size_limit</p>
|
||
</td>
|
||
<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.2 "><p id="ddm_03_0058__p24334532145">Size of a temporary table.</p>
|
||
</td>
|
||
<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.3 "><p id="ddm_03_0058__p2056673119453">500000–2000000000</p>
|
||
</td>
|
||
<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.4 "><p id="ddm_03_0058__p882131312410">1000000</p>
|
||
</td>
|
||
</tr>
|
||
<tr id="ddm_03_0058__row633512466142"><td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.1 "><p id="ddm_03_0058__p8430185381420">transaction_policy</p>
|
||
</td>
|
||
<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.2 "><p id="ddm_03_0058__p0430115351417">Transactions supported by DDM. XA transaction, which attempts to ensure atomicity and isolation. FREE transaction, which is a best-effort commit transaction that allows data to be written to multiple shards, without impacting performance. FREE transactions do not ensure atomicity. NO_DTX transaction, which is a single-shard transaction.</p>
|
||
</td>
|
||
<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.3 "><p id="ddm_03_0058__p9566103113451">XA, FREE, NO_DTX</p>
|
||
</td>
|
||
<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.4 "><p id="ddm_03_0058__p137681304114">XA</p>
|
||
</td>
|
||
</tr>
|
||
<tr id="ddm_03_0058__row183351646141420"><td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.1 "><p id="ddm_03_0058__p10430135351416">transfer_hash_to_mod_hash</p>
|
||
</td>
|
||
<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.2 "><p id="ddm_03_0058__p1843055318143">Whether the hash algorithm must be converted into mod_hash during table creation.</p>
|
||
</td>
|
||
<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.3 "><p id="ddm_03_0058__p175666312453">OFF or ON</p>
|
||
</td>
|
||
<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.4 "><p id="ddm_03_0058__p97361311417">OFF</p>
|
||
</td>
|
||
</tr>
|
||
<tr id="ddm_03_0058__row23207511148"><td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.1 "><p id="ddm_03_0058__p124316539143">ultimate_optimize</p>
|
||
</td>
|
||
<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.2 "><p id="ddm_03_0058__p12431165311419">Whether the SQL execution plan is optimized based on parameter values.</p>
|
||
</td>
|
||
<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.3 "><p id="ddm_03_0058__p7566113194512">OFF or ON</p>
|
||
</td>
|
||
<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.4 "><p id="ddm_03_0058__p1168171314113">ON</p>
|
||
</td>
|
||
</tr>
|
||
<tr id="ddm_03_0058__row1117510291211"><td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.1 "><p id="ddm_03_0058__p1617532919215">force_read_master_in_transaction</p>
|
||
</td>
|
||
<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.2 "><p id="ddm_03_0058__p217515290217">Whether SQL statements involved in each transaction are read from the master node.</p>
|
||
<p id="ddm_03_0058__p14836440151910">Note: This parameter is available in version 3.0.9 or later. If this feature is enabled in version 3.0.9 but the version is downgraded to 3.0.9 below, the feature keeps enabled when the version returns to 3.0.9 or later.</p>
|
||
</td>
|
||
<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.3 "><p id="ddm_03_0058__p45661031104519">OFF or ON</p>
|
||
</td>
|
||
<td class="cellrowborder" valign="top" width="25%" headers="mcps1.3.3.2.4.2.1.2.5.1.4 "><p id="ddm_03_0058__p417517291028">OFF</p>
|
||
</td>
|
||
</tr>
|
||
</tbody>
|
||
</table>
|
||
</div>
|
||
<p id="ddm_03_0058__p3667122916376">By default, DDM allows you to modify only the preceding instance parameters. If you need to modify other parameters in some special scenarios such as data migration, contact technical support.</p>
|
||
<div class="p" id="ddm_03_0058__p1625616811373">Parameter configuration examples:<div class="fignone" id="ddm_03_0058__fig9984104973517"><span class="figcap"><b>Figure 1 </b>Result if <strong id="ddm_03_0058__b98675569146">bind_table</strong> is not used</span><br><span><img id="ddm_03_0058__image198411495355" src="en-us_image_0000001685147610.png"></span></div>
|
||
</div>
|
||
<div class="fignone" id="ddm_03_0058__fig49841149193515"><span class="figcap"><b>Figure 2 </b>Result if <strong id="ddm_03_0058__b794915311515">bind_table</strong> is used</span><br><span><img id="ddm_03_0058__image19846491355" src="en-us_image_0000001685147602.png"></span></div>
|
||
</p></li><li id="ddm_03_0058__li14118373204"><span>Click <strong id="ddm_03_0058__b5788551121520">Save</strong> in the upper left corner and then <strong id="ddm_03_0058__b159911481150">Yes</strong> in the displayed dialog box.</span><p><div class="note" id="ddm_03_0058__note848718158396"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><ul id="ddm_03_0058__ul9487515193918"><li id="ddm_03_0058__li1248631513390">Modifying parameters may affect access to the DDM instance. Exercise caution when performing this operation.</li><li id="ddm_03_0058__li84871915133910">It takes 20s to 60s to have the modifications to take effect.</li></ul>
|
||
</div></div>
|
||
</p></li></ol>
|
||
</div>
|
||
</div>
|
||
<div>
|
||
<div class="familylinks">
|
||
<div class="parentlink"><strong>Parent topic:</strong> <a href="ddm_06_0001.html">Instance Management</a></div>
|
||
</div>
|
||
</div>
|
||
|