matches one of the bound SQL statements in the system table and the system variable tidb_use_plan_baselines is set to on (the default value is on), TiDB then uses the corresponding optimizer hint for this bindings for these queries. Enable capturing To enable baseline capturing, set tidb_capture_plan_baselines to on. The default value is off. Note: Because the automatic binding creation function relies capture_plan_baselines_blacklist �→ . Then the filtering conditions take effect in the entire cluster immediately. 1337 -- Filter by table name INSERT INTO mysql.capture_plan_baselines_blacklist(filter_type

“1024GB”. 2.2.1.3 Others 35 • Before the upgrade, check whether the value of the tidb_evolve_plan_baselines system variable is ON. If the value is ON, set it to OFF; otherwise, the upgrade will fail. • matches one of the bound SQL statements in the system table and the system variable tidb_use_plan_baselines is set to on (the default value is on), TiDB then uses the corresponding optimizer hint for this show warnings; 9.3.4.3.2 Baseline capturing To enable baseline capturing, set tidb_capture_plan_baselines to on. The default value is off. Note: Because the automatic binding creation function relies

matches one of the bound SQL statements in the system table and the system variable tidb_use_plan_baselines is set to on (the default value is on), TiDB then uses the 680 corresponding optimizer hint for warnings; 685 9.3.4.3.2 Baseline capturing To enable baseline capturing, set tidb_capture_plan_baselines to on. The default value is off. Note: Because the automatic binding creation function relies to enable automatic binding evolution: set global tidb_evolve_plan_baselines = on; The default value of tidb_evolve_plan_baselines is off. Warning: • Baseline evolution is an experimental feature.

compaction bytes 达到该阈值时， 流控机制开始 拒绝所有写入 请求并报错。 默认值为 “1024GB”。 2.2.1.3 其他 • 升级前，请检查系统变量tidb_evolve_plan_baselines 的值是否为 ON。如果为 ON，需要将其改成 OFF， 否则会导致升级失败。 • v4.0 集群升级到 v5.2 集群后，tidb_multi_statement_mode 变量的默认值由 SQL 进行 “标准化” 处理，然后存储到系统表中。在处理 SQL 查询时，只要 “标准化” 后的 SQL 和系统表中某个被绑 定的 SQL 语句一致，并且系统变量 tidb_use_plan_baselines 的值为 on（其默认值为 on），即可使用相应的优 化器 Hint。如果存在多个可匹配的执行计划，优化器会从中选择代价最小的一个进行绑定。 标准化：把 SQL 中的常量变成变量参数，对空格 select * from t; show warnings; 9.3.4.3.2 自动捕获绑定 (Baseline Capturing) 通过将 tidb_capture_plan_baselines 的值设置为 on（其默认值为 off）可以打开自动捕获绑定功能。 注意： 自动绑定功能依赖于Statement Summary，因此在使用自动绑定之前需打开 Statement Summary

matches one of the bound SQL statements in the system table and the system variable tidb_use_plan_baselines is set to on (the default value is on), TiDB then uses the corresponding optimizer hint for this bindings for these queries. Enable capturing To enable baseline capturing, set tidb_capture_plan_baselines to on. The default value is off. Note: 1615 Because the automatic binding creation function relies mysql.capture_plan_baselines_blacklist �→ . Then the filtering conditions take effect in the entire cluster immediately. -- Filter by table name INSERT INTO mysql.capture_plan_baselines_blacklist(filter_type

SQL 进行 “标准化” 处理，然后存储到系统表中。在处理 SQL 查询时，只要 “标准化” 后的 SQL 和系统表中某个被绑 定的 SQL 语句一致，并且系统变量tidb_use_plan_baselines 的值为 on（其默认值为 on），即可使用相应的优 化器 Hint。如果存在多个可匹配的执行计划，优化器会从中选择代价最小的一个进行绑定。 标准化：把 SQL 中的常量变成变量参数，对空格 (Baseline Capturing) 自动绑定会对符合捕获条件的查询进行捕获，为符合条件的查询生成相应的绑定。通常用于升级时的计划回 退防护。 使用方式 通过将 tidb_capture_plan_baselines 的值设置为 on（其默认值为 off）可以打开自动捕获绑定功能。 注意： 自动绑定功能依赖于Statement Summary，因此在使用自动绑定之前需打开 Statement Summary 括表名、频率和用户名。 使用方式 将过滤规则插入到系统表 mysql.capture_plan_baselines_blacklist 中，该过滤规则即刻起会在整个集群范 围内生效。 -- 按照表名进行过滤 INSERT INTO mysql.capture_plan_baselines_blacklist(filter_type, filter_value) VALUES('table'

matches one of the bound SQL statements in the system table and the system variable tidb_use_plan_baselines is set to on (the default value is on), TiDB then uses the corresponding optimizer hint for this warnings; 793 9.3.4.3.2 Baseline capturing To enable baseline capturing, set tidb_capture_plan_baselines to on. The default value is off. Note: Because the automatic binding creation function relies to enable automatic binding evolution: set global tidb_evolve_plan_baselines = on; The default value of tidb_evolve_plan_baselines is off. Warning: • Baseline evolution is an experimental feature.

global_variables) • Other system tables +-----------------------------------------------------+ | capture_plan_baselines_blacklist | | column_stats_usage | | gc_delete_range | | gc_delete_range_done | | global_variables matches one of the bound SQL statements in the system table and the system variable tidb_use_plan_baselines is set to on (the default value is on), TiDB then uses the corresponding optimizer hint for this reproduce an execution plan. Enable capturing To enable baseline capturing, set tidb_capture_plan_baselines to on. The default value is off. Note: Because the automatic binding creation function relies

global_variables) • Other system tables +-----------------------------------------------------+ | capture_plan_baselines_blacklist | | column_stats_usage | | gc_delete_range | | gc_delete_range_done | | global_variables matches one of the bound SQL statements in the system table and the system variable tidb_use_plan_baselines is set to on (the default value is on), TiDB then uses the corresponding optimizer hint for this reproduce an execution plan. Enable capturing To enable baseline capturing, set tidb_capture_plan_baselines to on. The default value is off. Note: Because the automatic binding creation function relies

global_variables) • Other system tables +-----------------------------------------------------+ | capture_plan_baselines_blacklist | | column_stats_usage | | gc_delete_range | | gc_delete_range_done | | global_variables matches one of the bound SQL statements in the system table and the system variable tidb_use_plan_baselines is set to on (the default value is on), TiDB then uses the corresponding optimizer hint for this reproduce an execution plan. Enable capturing To enable baseline capturing, set tidb_capture_plan_baselines to on. The default value is off. Note: Because the automatic binding creation function relies