. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 4 Fast vttablet state transitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 7 Current state of monitoring 111 1. Vitess status pages . . . . . . . . . . . . . . . . . . . . . . . . . . . . instead will share the underlying connection between users. This means that it’s not safe to store any state in the session as you can’t be sure it will continue executing queries on the same connection, and

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 OnlineDDL & VTTablet state manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 Fast vttablet state transitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134 Current state of monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 Fast vttablet state transitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 Current state of monitoring 101 1. Vitess status pages . . . . . . . . . . . . . . . . . . . . . . . . . . . . instead will share the underlying connection between users. This means that it’s not safe to store any state in the session as you can’t be sure it will continue executing queries on the same connection, and

· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 324 7.2.1 Use the state interface· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 324 Hibernate Region feature by default. If a Region is in an inactive state for a long time, it is automatically set to a silent state, which reduces the system overhead of the heartbeat information between INDEX person_unique_id; Note: DDL operations are not transactions. You don’t need to run a COMMIT state- ment when executing DDL operations. 85 3.2.5 Insert, update, and delete data Common DML features

interval �→ Modified Controls the running frequency at which repli- caChecker checks the health state of a Region. The smaller this value is, the faster repli- caChecker runs. Normally, you do not need INDEX person_unique_id; Note: DDL operations are not transactions. You don’t need to run a COMMIT state- ment when executing DDL operations. 3.3.5 Insert, update, and delete data Common DML features are the firewall status. Take CentOS Linux release 7.7.1908 (Core) as an example. sudo firewall-cmd --state sudo systemctl status firewalld.service 2. Stop the firewall service. sudo systemctl stop firewalld

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 Fast vttablet state transitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 Current state of monitoring 91 1. Vitess status pages . . . . . . . . . . . . . . . . . . . . . . . . . . . . instead will share the underlying connection between users. This means that it’s not safe to store any state in the session as you can’t be sure it will continue executing queries on the same connection, and

corresponding to a SQL digest. – Add the TIDB_DECODE_SQL_DIGESTS function to query the normalized SQL state- ments (a form without formats and arguments) corresponding to a set of SQL digests in the cluster distinguishing query-executing transactions from idle transactions on the TIDB_TRX system table. The Normal state is now divided into Running and Idle states. User documents: 37 - View the pessimistic lock-waiting in correlated subqueries is wrong #25799 • TiKV – Fix the wrong tikv_raftstore_hibernated_peer_state metric #10330 – Fix the wrong arguments type of the json_unquote() function in the coprocessor #10176

only uses statistics of some columns (such as columns in the WHERE, JOIN, ORDER BY, and GROUP BY state- ments). These used columns are called PREDICATE COLUMNS. Since v5.4.0, you can set the value of INDEX person_unique_id; Note: DDL operations are not transactions. You don’t need to run a COMMIT state- ment when executing DDL operations. 3.3.5 Insert, update, and delete data Common DML features are the firewall status. Take CentOS Linux release 7.7.1908 (Core) as an example. sudo firewall-cmd --state sudo systemctl status firewalld.service 2. Stop the firewall service. sudo systemctl stop firewalld

whether to re- turn er- ror im- me- di- ately when an er- ror oc- curs in a non- transactional DML state- ment. 54 Variable name Change type Description tidb_prepared_plan_cache_memory_guard_ratio �→ tions across in- stances) fea- ture. When the value is true �→ , both KILL �→ and KILL �→ �→ TIDB �→ state- ments can ter- mi- nate queries or con- nec- tions across in- stances so you do not need to worry INDEX person_unique_id; Note: DDL operations are not transactions. You don’t need to run a COMMIT state- ment when executing DDL operations. 3.3.5 Insert, update, and delete data Common DML features are

�→ Modified Takes effect start- ing from v6.5.0. It con- trols whether read opera- tions in SQL state- ments con- taining INSERT �→ , DELETE �→ , and UPDATE can be pushed down to Ti- Flash. The default mem- ory quota for a query. For TiDB v6.5.0 and later ver- sions, to control the mem- ory of DML state- ments more accu- rately, this vari- able is used to set the thresh- old value of mem- ory quota for used to set the concur- rency of scan opera- tions per- formed when TiDB exe- cutes inter- nal SQL state- ments (such as an auto- matic update of statis- tics). The default value is 1. 62 Variable name