TiDB 4.0.11 Release Notes

Release date: February 26, 2021

TiDB version: 4.0.11

New Features

• TiDB

  • Support the utf8_unicode_ci and utf8mb4_unicode_ci collations #22558

• TiKV

  • Support the utf8mb4_unicode_ci collation #9577
  • Support the cast_year_as_time collation #9299

• TiFlash

  • Add a Coprocessor thread pool to queue Coprocessor requests for execution, which avoids out of memory (OOM) in some cases, and add the cop_pool_size and batch_cop_pool_size configuration items with the default values of NumOfPhysicalCores * 2

Improvements

• TiDB

  • Reorder inner joins that are simplified from outer joins #22402
  • Support multiple clusters in Grafana dashboards #22534
  • Add a workaround for the issue of multiple statements #22468
  • Divide the metrics of slow query into internal and general #22405
  • Add interface for utf8_unicode_ci and utf8mb4_unicode_ci collations #22099

• TiKV

  • Add metrics of server information for DBaaS #9591
  • Support multiple clusters in Grafana dashboards #9572
  • Report RocksDB metrics to TiDB #9316
  • Record the suspension time for Coprocessor tasks #9277
  • Add thresholds of key counts and key size for Load Base Split #9354
  • Check whether the file exists before data import #9544
  • Improve Fast Tune panels #9180

• PD

  • Support multiple clusters in Grafana dashboards #3398

• TiFlash

  • Optimize the performance of the date_format function
  • Optimize the memory consumption of handling ingest SST
  • Optimize the retrying logic in Batch Coprocessor to reduce the probability of Region error

• Tools

  • TiCDC

    • Add the version information in the capture metadata and add the CLI version of a changefeed in the changefeed metadata #1342

  • TiDB Lightning

    • Create tables in parallel to improve import performance #502
    • Skip splitting Regions to improve import performance if the engine's total size is smaller than the Region size #524
    • Add a import progress bar and optimize the accuracy of restore progress #506

Bug Fixes

• TiDB

  • Fix the issue of abnormal unicode_ci constant propagation #22614
  • Fix the issue that might cause wrong collation and coercibility #22602
  • Fix the issue that might cause wrong collation results #22599
  • Fix the issue of constant substitution for different collations #22582
  • Fix a bug that the like function might return wrong result when using collation #22531
  • Fix the issue of incorrect duration type inference in least and greatest functions #22580
  • Fix a bug that occurs when the like function handles a single character wildcard (_) followed by a multiple character wildcard (%) #22575
  • Fix the type inference error of the TiDB's built-in functions (least and greatest) #22562
  • Fix a bug that makes the like function get the wrong result if the pattern string is a unicode string #22529
  • Fix a bug that the point get query does not get the snapshot data when the @@tidb_snapshot variable is set #22527
  • Fix the potential panic that occurs when generating hints from joins #22518
  • Fix the issue that strings are incorrectly converted to the BIT type #22420
  • Fix the index out of range error that occurs when inserting values to the tidb_rowid column #22359
  • Fix a bug that the cached plan is incorrectly used #22353
  • Fix the runtime panic in the WEIGHT_STRING function when the length of the binary/char string is too large #22332
  • Forbid using the generated column when the number of function parameters is invalid #22174
  • Correctly set the process information before building the execution plan #22148
  • Fix the issue of inaccurate runtime statistics of IndexLookUp #22136
  • Add cache for the memory usage information when the cluster is deployed in a container #22116
  • Fix the issue of the decoding plan errors #22022
  • Report errors for using invalid window specifications #21976
  • Report errors when the PREPARE statement is nested with EXECUTE, DEALLOCATE or PREPARE #21972
  • Fix the issue that no error is reported when the INSERT IGNORE statement is used on a non-existing partition #21971
  • Unify the encoding of EXPLAIN results and slow log #21964
  • Fix the issue of unknown columns in join when using the aggregate operator #21957
  • Fix the wrong type inference in the ceiling function #21936
  • Fix the issue that the Double type column ignores its decimal #21916
  • Fix the issue that the correlated aggregation is calculated in subqueries #21877
  • Report errors for the JSON object with key length >= 65536 #21870
  • Fix the issue that the dyname function is incompatible with MySQL #21850
  • Fix the issue that the to_base64 function returns NULL when the input data is too long #21813
  • Fix the failure of comparing multiple fields in the subquery #21808
  • Fix the issue that occurs when comparing the float type in JSON #21785
  • Fix the issue that occurs when comparing the types of JSON objects #21718
  • Fix the issue that the coercibility value of the cast function is incorrectly set #21714
  • Fix an unexpected panic when using the IF function #21711
  • Fix the issue that the NULL result returned from JSON search is incompatible with MySQL #21700
  • Fix the issue that occurs when checking the only_full_group_by mode using ORDER BY and HAVING #21697
  • Fix the issue that the units of Day and Time are incompatible with MySQL #21676
  • Fix the issue that the default values of LEAD and LAG cannot adapt to the field type #21665
  • Perform a check to ensure that the LOAD DATA statement can only load data into base tables #21638
  • Fix the issue that occurs when addtime and subtime functions handle invalid arguments #21635
  • Change the round rule for approximate values to "round to the nearest even number" #21628
  • Fix the issue that WEEK() does not recognize @@GLOBAL.default_week_format until it has been explicitly read #21623

• TiKV

  • Fix the issue that TiKV is failed to build with PROST=1 #9604
  • Fix the unmatched memory diagnostics #9589
  • Fix the issue that the end key of a partial RawKV-restore range is inclusive #9583
  • Fix the issue of TiKV panic that occurs when loading the old value of a key of a rolled-back transaction during TiCDC's incremental scan #9569
  • Fix the configuration glitch of old values when changefeeds with different settings connect to one Region #9565
  • Fix a crash issue that occurs when running a TiKV cluster on a machine with a network interface that lacks the MAC address (introduced in v4.0.9) #9516
  • Fix the issue of TiKV OOM when backing up a huge Region #9448
  • Fix the issue that region-split-check-diff cannot be customized #9530
  • Fix the issue of TiKV panic when the system time goes back #9542

• PD

  • Fix the issue that member health metrics are incorrectly displayed #3368
  • Forbid removing the tombstone store that still has peers #3352
  • Fix the issue that the store limit cannot be persisted #3403
  • Fix the limit constriction of the scatter range scheduler #3401

• TiFlash

  • Fix a bug that the min/max result is wrong for the decimal type
  • Fix a bug that TiFlash might crash when reading data
  • Fix the issue that some data written after DDL operations might be lost after data compaction
  • Fix the issue that TiFlash incorrectly handles decimal constants in Coprocessor
  • Fix the potential crash during the learner read process
  • Fix the inconsistent behaviors of division by 0 or NULL between TiDB and TiFlash

• Tools

  • TiCDC

    • Fix a bug that the TiCDC service might unexpectedly exit when ErrTaskStatusNotExists and the closing of capture session occur at the same time #1240
    • Fix the old value switch issue that a changefeed might be affected by another changefeed #1347
    • Fix a bug that the TiCDC service might hang when processing a new changefeed with the invalid sort-engine parameter #1309
    • Fix the issue of panic that occurs when getting the debugging information on non-owner nodes #1349
    • Fix the issue that the ticdc_processor_num_of_tables and ticdc_processor_table_resolved_ts metrics are not properly updated when adding or removing tables #1351
    • Fix the issue of potential data loss if a processor crashes when adding a table #1363
    • Fix a bug that the owner might lead to abnormal TiCDC server exits during table migrations #1352
    • Fix a bug that TiCDC does not exit in time after the service GC safepoint is lost #1367
    • Fix a bug that the KV client might skip creating the event feed #1336
    • Fix a bug that the atomicity of transactions is broken when the transactions are replicated to the downstream #1375

  • Backup & Restore (BR)

    • Fix the issue that TiKV might be caused to generate a big Region after BR restores the backup #702
    • Fix the issue that BR restores a table's Auto ID even if the table does not have Auto ID #720

  • TiDB Lightning

    • Fix a bug that column count mismatch might be triggered when using the TiDB-backend #535
    • Fix a bug that TiDB-backend panics if the column count of the source file and the column count of the target table mismatch #528
    • Fix a bug that TiKV might unexpectedly panic during TiDB Lightning's data import #554