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TiDB 3.0.8 Release Notes

Release date: December 31, 2019

TiDB version: 3.0.8

TiDB Ansible version: 3.0.8


  • SQL Optimizer
    • Fix the wrong SQL binding plan caused by untimely cache updates #13891
    • Fix the issue that the SQL binding might be invalid when an SQL statement contains a symbol list #14004
    • Fix the issue that an SQL binding cannot be created or deleted because an SQL statement ends with ; #14113
    • Fix the issue that a wrong SQL query plan might be selected because the PhysicalUnionScan operator sets wrong statistics #14133
    • Remove the minAutoAnalyzeRatio restriction to make autoAnalyze more timely #14015
  • SQL Execution Engine
    • Fix issues that the INSERT/REPLACE/UPDATE ... SET ... = DEFAULT syntax might report an error and combining the usage of the DEFAULT expression with a virtual generated column might report an error #13682
    • Fix the issue that the INSERT statement might report an error when converting a string to a float #14011
    • Fix the issue that sometimes the aggregate operation is low effective because the concurrency value of the HashAgg executor is incorrectly initialized #13811
    • Fix the issue that an error is reported in the execution ofgroup by item when the clause is in the parentheses #13658
    • Fix the issue that the execution of OUTER JOIN might report an error because TiDB incorrectly calculates group by item #14014
    • Fix the issue that the error message is inaccurate when Range-exceeding data is written into Range partitioned tables #14107
    • Revert PR #10124 and cancel the PadCharToFullLength effect to avoid unexpected query results in special cases, considering that MySQL 8 will discard PadCharToFullLength soon #14157
    • Fix the goroutine leak issue when executing the EXPLAIN ANALYZE statement caused by unguaranteed close() calling in ExplainExec #14226
  • DDL
    • Optimize the error message output of change column/modify column to make it easier to understand #13796
    • Add the SPLIT PARTITION TABLE syntax to support splitting Regions for partitioned tables #13929
    • Fix the issue that the index length exceeds 3072 bytes and no error is reported because the index length is incorrectly checked when an index is created #13779
    • Fix the issue that the GC life time is shorter than transaction duration error message might be reported because it takes too much time to add an index in partitioned tables #14132
    • Fix the panic when SELECT * FROM information_schema.KEY_COLUMN_USAGE is executed because the foreign key is not checked when DROP COLUMN/MODIFY COLUMN/CHANGE COLUMN is executed #14105
  • Server
    • Statement Summary improvements:
      • Add a large number of SQL metric fields to facilitate analyzing SQL statements in more detail #14151, #14168
      • Add the stmt-summary.refresh-interval parameter to control whether to move the stale data from the events_statements_summary_by_digest table to the events_statements_summary_by_digest_history table (the default interval: 30 minutes) #14161
      • Add the events_statements_summary_by_digest_history table to save the stale data in events_statements_summary_by_digest #14166
    • Fix the issue that the binlog is incorrectly output when RBAC-related internal SQL statements are executed #13890
    • Add the server-version configuration item to control the feature of modifying the TiDB server version #13906
    • Add the feature of using the HTTP interface to recover writing the TiDB binlog #13892
    • Update the privilege required by GRANT roles TO user from GrantPriv to ROLE_ADMIN or SUPER, to keep consistency with the MySQL behavior #13932
    • Modify the TiDB behavior from using the current database to reporting the No database selected error when the GRANT statement does not specify a database name, to keep compatibility with the MySQL behavior #13784
    • Modify the execution privilege for the REVOKE statement from SuperPriv to REVOKE being executable only if the user has the privilege for the corresponding schema, to keep consistency with the MySQL behavior #13306
    • Fix the issue that GrantPriv is mistakenly granted to the target user when the GRANT ALL syntax does not contain WITH GRANT OPTION #13943
    • Fix the issue that the error message does not contain the cause for the LOAD DATA statement’s wrong behavior when LoadDataInfo fails to call addRecord #13980
    • Fix the issue that wrong slow query information is output because multiple SQL statements in a query share the same StartTime #13898
    • Fix the issue that the memory might leak when batchClient processes a large transaction #14032
    • Fix the issue that system_time_zone is always displayed as CST and now TiDB’s system_time_zone is obtained from systemTZ in the mysql.tidb table #14086
    • Fix the issue that the GRANT ALL syntax does not grant all privileges to the user #14092
    • Fix the issue that the Priv_create_user privilege is invalid for CREATE ROLE and DROP ROLE #14088
    • Modify the error code of ErrInvalidFieldSize from 1105(Unknow Error) to 3013 #13737
    • Add the SHUTDOWN command to stop a TiDB server and add the ShutdownPriv privilege #14104
    • Fix the atomicity issue for the DROP ROLE statement to avoid some roles being deleted unexpectedly when TiDB fails to execute a statement #14130
    • Fix the issue that the tidb_enable_window_function in the SHOW VARIABLE result incorrectly outputs 1 when a TiDB version is upgraded to 3.0, and replace the wrong result with 0 #14131
    • Fix the issue that the goroutine might leak because gcworker continuously retries when the TiKV node is offline #14106
    • Record the binlog Prewrite time in the slow query log to improve the usability for issue tracking #14138
    • Make the tidb_enable_table_partition variable support GLOBAL SCOPE #14091
    • Fix the issue that the user privilege might be missing or mistakenly added because the newly added privilege is not correctly granted to the corresponding user when a new privilege is added #14178
    • Fix the issue that the CheckStreamTimeoutLoop goroutine might leak because rpcClient does not close when the TiKV server is disconnected #14227
    • Support certificate-based authentication (User document) #13955
  • Transaction
    • Update the default value of the tidb_txn_mode variable from "" to "pessimistic" when a new cluster is created #14171
    • Fix the issue that the lock waiting time is too long for a pessimistic transaction because the lock waiting time for a single statement is not reset when a transaction is retried #13990
    • Fix the issue that wrong data might be read because unmodified data is unlocked for the pessimistic transaction mode #14050
    • Fix repeated insert value restriction checks because transaction types are not distinguished when prewrite is performed in mocktikv #14175
    • Fix the panic because transactions are not correctly handled when session.TxnState is Invalid #13988
    • Fix the issue that the ErrConfclit structure in mocktikv does not contain ConflictCommitTS #14080
    • Fix the issue that the transaction is blocked because TiDB does not correctly check lock timeout after resolving the lock #14083
  • Monitor
    • Add the pessimistic_lock_keys_duration monitoring item in LockKeys #14194


  • Coprocessor
    • Modify the level of the output log from error to warn when an error occurs in Coprocessor #6051
    • Modify the update behavior of statistics sampling data from directly updating the row to deleting before inserting, to keep consistency with the update behavior of tidb-server #6069
  • Raftstore
    • Fix the panic caused by repeatedly sending the destroy message to peerfsm and peerfsm being destroyed multiple times #6297
    • Update the default value of split-region-on-table from true to false to disable splitting Regions by table by default #6253
  • Engine
    • Fix the issue that empty data might be returned because RocksDB iterator errors are not correctly processed in extreme conditions #6326
  • Transaction
    • Fix the issue that TiKV fails to write data into keys and GC is blocked because the pessimistic locks are incorrectly cleaned up #6354
    • Optimize the pessimistic lock waiting mechanism to improve the performance in scenarios where the lock conflict is severe #6296
  • Update the default value of tikv_alloc from tikv_alloc/default to jemalloc #6206


  • Client
    • Support using context to create a client and setting the timeout duration when creating a new client #1994
    • Support creating the KeepAlive connection #2035
  • Optimize the performance for the /api/v1/regions API #1986
  • Fix the issue that deleting stores in a tombstone state might cause a panic #2038
  • Fix the issue that overlapped Regions are mistakenly deleted when loading the Region information from disks #2011, #2040
  • Upgrade etcd from v3.4.0 to v3.4.3 (note that after upgrading you can only degrade etcd using pd-recover) #2058


  • TiDB Binlog
    • Fix the issue that the binlog is ignored because Pump does not receive the DDL committed binlog #853

TiDB Ansible

  • Revert the simplified configuration item #1053
  • Optimize the logic for checking the TiDB version when performing a rolling update #1056
  • Upgrade TiSpark to v2.1.8 #1061
  • Fix the issue that the PD role monitoring item is wrongly displayed on Grafana #1065
  • Optimize Thread Voluntary Context Switches and Thread Nonvoluntary Context Switches monitoring items on the TiKV Detail page on Grafana #1071
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