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TiDB 3.0.2 Release Notes

Release date: August 7, 2019

TiDB version: 3.0.2

TiDB Ansible version: 3.0.2

TiDB

SQL Optimizer
- Fix the issue that the “Can’t find column in schema” message is reported when the same table occurs multiple times in a query and logically the query result is always empty #11247
- Fix the issue that the query plan does not meet the expectation caused by the TIDB_INLJ hint not working correctly in some cases (like explain select /*+ TIDB_INLJ(t1) */ t1.b, t2.a from t t1, t t2 where t1.b = t2.a) #11362
- Fix the issue that the column name in the query result is wrong in some cases (like SELECT IF(1,c,c) FROM t) #11379
- Fix the issue that some queries like SELECT 0 LIKE 'a string' return TRUE because the LIKE expression is implicitly converted to 0 in some cases #11411
- Support sub-queries in the SHOW statement, like SHOW COLUMNS FROM tbl WHERE FIELDS IN (SELECT 'a') #11459
- Fix the issue that the related column of the aggregate function cannot be found and an error is reported caused by the outerJoinElimination optimizing rule not correctly handling the column alias; improve alias parsing in the optimizing process to make optimization cover more query types #11377
- Fix the issue that no error is reported when the syntax restriction is violated in the Window function (for example, UNBOUNDED PRECEDING is not allowed to appear at the end of the Frame definition) #11543
- Fix the issue that FUNCTION_NAME is in uppercase in the ERROR 3593 (HY000): You cannot use the window function FUNCTION_NAME in this context error message, which causes incompatibility with MySQL #11535
- Fix the issue that the unimplemented IGNORE NULLS syntax in the Window function is used but no error is reported #11593
- Fix the issue that the Optimizer does not correctly estimate time equal conditions #11512
- Support updating the Top-N statistics based on the feedback information #11507
SQL Execution Engine
- Fix the issue that the returned value is not NULL when the INSERT function contains NULL in parameters #11248
- Fix the issue that the computing result might be wrong when the partitioned table is checked by the ADMIN CHECKSUM operation #11266
- Fix the issue that the result might be wrong when INDEX JOIN uses the prefix index #11246
- Fix the issue that result might be wrong caused by incorrectly aligning fractions when the DATE_ADD function does subtraction on date numbers involving microseconds #11288
- Fix the wrong result caused by the DATE_ADD function incorrectly processing the negative numbers in INTERVAL #11325
- Fix the issue that the number of fractional digits returned by Mod(%), Multiple(*) or Minus(-) is different from that in MySQL when Mod(%), Multiple(*) or Minus(-) returns 0 and the number of fractional digits is large (like select 0.000 % 0.11234500000000000000) #11251
- Fix the issue that NULL with a warning is incorrectly returned when the length of the result returned by CONCAT and CONCAT_WS functions exceeds max_allowed_packet #11275
- Fix the issue that NULL with a warning is incorrectly returned when parameters in the SUBTIME and ADDTIME functions are invalid #11337
- Fix the issue that NULL is incorrectly returned when parameters in the CONVERT_TZ function are invalid #11359
- Add the MEMORY column to the result returned by EXPLAIN ANALYZE to show the memory usage of this query #11418
- Add CARTESIAN Join to the result of EXPLAIN #11429
- Fix the incorrect data of auto-increment columns of the float and double types #11385
- Fix the panic issue caused by some nil information when pseudo statistics are dumped #11460
- Fix the incorrect query result of SELECT … CASE WHEN … ELSE NULL ... caused by constant folding optimization #11441
- Fix the issue that floatStrToIntStr does not correctly parse the input such as +999.9999e2 #11473
- Fix the issue that NULL is not returned in some cases when the result of the DATE_ADD and DATE_SUB function overflows #11476
- Fix the issue that the conversion result is different from that in MySQL if the string contains an invalid character when a long string is converted to an integer #11469
- Fix the issue that the result of the REGEXP BINARY function is incompatible with MySQL caused by case sensitiveness of this function #11504
- Fix the issue that an error is reported when the GRANT ROLE statement receives CURRENT_ROLE; fix the issue that the REVOKE ROLE statement does not correctly revoke the mysql.default_role privilege #11356
- Fix the display format issue of the Incorrect datetime value warning information when executing statements like SELECT ADDDATE('2008-01-34', -1) #11447
- Fix the issue that the error message reports constant … overflows float rather than constant … overflows bigint if the result overflows when a float field of the JSON data is converted to an integer #11534
- Fix the issue that the result might be wrong caused by incorrect type conversion when the DATE_ADD function receives FLOAT, DOUBLE and DECIMAL column parameters #11527
- Fix the wrong result caused by incorrectly processing the sign of the INTERVAL fraction in the DATE_ADD function #11615
- Fix the incorrect query result when Index Lookup Join contains the prefix index caused by Ranger not correctly handling the prefix index #11565
- Fix the issue that the “Incorrect arguments to NAME_CONST” message is reported if the NAME_CONST function is executed when the second parameter of NAME_CONST is a negative number #11268
- Fix the issue that the result is incompatible with MySQL when an SQL statement involves computing the current time and the value is fetched multiple times; use the same value when fetching the current time for the same SQL statement #11394
- Fix the issue that Close is not called for ChildExecutor when the Close of baseExecutor reports an error. This issue might lead to Goroutine leaks when the KILL statements do not take effect and ChildExecutor is not closed #11576
Server
- Fix the issue that the auto-added value is 0 instead of the current timestamp when LOAD DATA processes the missing TIMESTAMP field in the CSV file #11250
- Fix issues that the SHOW CREATE USER statement does not correctly check related privileges, and USER and HOST returned by SHOW CREATE USER CURRENT_USER() might be wrong #11229
- Fix the issue that the returned result might be wrong when executeBatch is used in JDBC #11290
- Reduce printing the log information of the streaming client when changing the TiKV server’s port #11370
- Optimize the logic of reconnecting the streaming client to the TiKV server so that the streaming client will not be blocked for a long time #11372
- Add REGION_ID in INFORMATION_SCHEMA.TIDB_HOT_REGIONS #11350
- Cancel the timeout duration of obtaining Region information from the PD API to ensure that obtaining Region information will not end in a failure when TiDB API http://{TiDBIP}:10080/regions/hot is called due to PD timeout when the number of Regions is large #11383
- Fix the issue that Region related requests do not return partitioned table-related Regions in the HTTP API #11466
- Make the following changes to reduce the probability of locking timeout caused by slow operations when the user manually validates pessimistic locking #11521:
  - Increase the default TTL of pessimistic locking from 30 seconds to 40 seconds
  - Increase the maximum TTL from 60 seconds to 120 seconds
  - Calculate the pessimistic locking duration from the first LockKeys request
- Change the SendRequest function logic in the TiKV client: try to immediately connect to another peer instead of keeping waiting when the connect cannot be built #11531
- Optimize the Region cache: label the removed store as invalid when a store is moved while another store goes online with a same address, to update the store information in the cache as soon as possible #11567
- Add the Region ID to the result returned by the http://{TiDB_ADDRESS:TIDB_IP}/mvcc/key/{db}/{table}/{handle} API #11557
- Fix the issue that Scatter Table does not work caused by the Scatter Table API not escaping the Range key #11298
- Optimize the Region cache: label the store where the Region exists as invalid when the correspondent store is inaccessible, to avoid reduced query performance caused by accessing this store #11498
- Fix the error that the table schema can still be obtained through the HTTP API after dropping the database with the same name multiple times #11585
DDL
- Fix the issue that an error occurs when a non-string column with a zero length is being indexed #11214
- Disallow modifying the columns with foreign key constraints and full-text indexes (Note: TiDB still supports foreign key constraints and full-text indexes in syntax) #11274
- Fix the issue that the index offset of the column might be wrong because the position changed by the ALTER TABLE statement and the default value of the column are used concurrently #11346
- Fix two issues that occur when parsing JSON files:
  - int64 is used as the intermediate parsing result of uint64 in ConvertJSONToFloat, which leads to the precision overflow error #11433
  - int64 is used as the intermediate parsing result of uint64 in ConvertJSONToInt, which leads to the precision overflow error #11551
- Disallow dropping indexes on the auto-increment column to avoid that the auto-increment column might get an incorrect result #11399
- Fix the following issues #11492:
  - The character set and the collation of the column are not consistent when explicitly specifying the collation but not the character set
  - The error is not correctly reported when there is a conflict between the character set and the collation that are specified by ALTER TABLE … MODIFY COLUMN
  - Incompatibility with MySQL when using ALTER TABLE … MODIFY COLUMN to specify character sets and collations multiple times
- Add the trace details of the subquery to the result of the TRACE query #11458
- Optimize the performance of executing ADMIN CHECK TABLE and greatly reduce its execution time #11547
- Add the result returned by SPLIT TABLE … REGIONS/INDEX and make TOTAL_SPLIT_REGION and SCATTER_FINISH_RATIO display the number of Regions that have been split successfully before timeout in the result #11484
- Fix the issue that the precision displayed by statements like SHOW CREATE TABLE is incomplete when ON UPDATE CURRENT_TIMESTAMP is the column attribute and the float precision is specified #11591
- Fix the issue that the index result of the column cannot be correctly calculated when the expression of a virtual generated column contains another virtual generated column #11475
- Fix the issue that the minus sign cannot be added after VALUE LESS THAN in the ALTER TABLE … ADD PARTITION … statement #11581
Monitor
- Fix the issue that data is not collected and reported because the TiKVTxnCmdCounter monitoring metric is not registered #11316
- Add the BindUsageCounter, BindTotalGauge and BindMemoryUsage monitoring metrics for the Bind Info #11467

TiKV

Fix the bug that TiKV panics if the Raft log is not written in time #5160
Fix the bug that the panic information is not written into the log file after TiKV panics #5198
Fix the bug that the Insert operation might be incorrectly performed in the pessimistic transaction #5203
Lower the output level of some logs that require no manual intervention to INFO #5193
Improve the accuracy of monitoring the storage engine size #5200
Improve the accuracy of the Region size in tikv-ctl #5195
Improve the performance of the deadlock detector for pessimistic locking #5192
Improve the performance of GC in the Titan storage engine #5197

PD

Fix the bug that the Scatter Region scheduler cannot work #1642
Fix the bug that the merge Region operation cannot be performed in pd-ctl #1653
Fix the bug that the remove-tombstone operation cannot be performed in pd-ctl #1651
Fix the issue that the Region overlapping with the key scope cannot be found when performing the scan Region operation #1648
Add the retrying mechanism to make sure that the members are added successfully in PD #1643

Tools

TiDB Binlog

Add the configuration item check feature when starting, which will stop the Binlog service and report an error when an invalid item is found #687
Add the node-id configuration in Drainer to specify a specific logic used by Drainer #684

TiDB Lightning

Fix the issue that tikv_gc_life_time fails to be changed back to its original value when 2 checksums are running at the same time #218
Add the configuration item check feature when starting, which will stop the Binlog service and report an error when an invalid item is found #217

TiDB Ansible

Fix the unit error that the Disk Performance monitor treats seconds as milliseconds #840
Add the log4j configuration file in Spark #841
Fix the issue that the Prometheus configuration file is generated in the wrong format when Binlog is enabled and Kafka or ZooKeeper is configured #844
Fix the issue that the pessimistic-txn configuration parameter is left out in the generated TiDB configuration file #850
Add and optimize metrics on the TiDB Dashboard #853
Add descriptions for each monitoring item on the TiDB Dashboard #854
Add the TiDB Summary Dashboard to better view the cluster status and troubleshoot issues #855
Update the Allocator Stats monitoring item on the TiKV Dashboard #857
Fix the unit error in the Node Exporter’s alerting expression #860
Upgrade the TiSpark jar package to v2.1.2 #862
Update the descriptions of the Ansible Task feature #867
Update the expression of the local reader requests monitoring item on the TiDB Dashboard #874
Update the expression of the TiKV Memory monitoring item on the Overview Dashboard, and fix the issue of wrongly displayed monitoring #879
Remove the Binlog support in the Kafka mode #878
Fix the issue that PD fails to transfer the Leader when executing the rolling_update.yml operation #887