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TiDB 4.0.6 Release Notes

Release date: September 15, 2020

TiDB version: 4.0.6

New Features

  • TiFlash

    • Support outer join in TiFlash broadcast join

  • TiDB Dashboard

    • Add Query Editor and execution UI (experimental) #713
    • Support store location topology visualization #719
    • Add cluster configuration UI (experimental) #733
    • Support sharing the current session #741
    • Support displaying the number of execution plans in SQL Statement list #746

  • Tools

    • TiCDC (GA since v4.0.6)

Improvements

  • TiDB

    • Replace error codes and messages with standard errors #19888
    • Improve the write performance of partitioned table #19649
    • Record more RPC runtime information in Cop Runtime statistics #19264
    • Forbid creating tables in metrics_schema and performance_schema #19792
    • Support adjusting the concurrency of the union executor #19886
    • Support out join in broadcast join #19664
    • Add SQL digest for the process list #19829
    • Switch to the pessimistic transaction mode for autocommit statement retry #19796
    • Support the %r and %T data format in Str_to_date() #19693
    • Enable SELECT INTO OUTFILE to require the file privilege #19577
    • Support the stddev_pop function #19541
    • Add the TiDB-Runtime dashboard #19396
    • Improve compatibility for the ALTER TABLE algorithms #19364
    • Encode insert/delete/update plans in the slow log plan field #19269

  • TiKV

    • Reduce QPS drop when DropTable or TruncateTable is being executed #8627
    • Support generating metafile of error codes #8619
    • Add performance statistics for cf scan details #8618
    • Add the rocksdb perf context panel in the Grafana default template #8467

  • PD

  • TiFlash

    • Add Grafana panels for data replication (apply Region snapshots and ingest SST files)
    • Add Grafana panels for write stall
    • Add dt_segment_force_merge_delta_rows and dt_segment_force_merge_delta_deletes to adjust the threshold of write stall
    • Support setting raftstore.snap-handle-pool-size to 0 in TiFlash-Proxy to disable applying Region snapshot by multi-thread to reduce memory consumption during data replication
    • Support CN check on https_port and metrics_port

  • Tools

    • TiCDC

      • Skip resolved lock during puller initialization #910
      • Reduce PD write frequency #937

    • Backup & Restore (BR)

      • Add real time cost in summary log #486

    • Dumpling

      • Support outputting INSERT with column names #135
      • Unify the --filesize and --statement-size definitions with those of mydumper #142

    • TiDB Lightning

      • Split and ingest Regions in more precise sizes #369

    • TiDB Binlog

      • Support setting GC time in go time package format #996

Bug Fixes

  • TiDB

    • Fix an issue of collecting the tikv_cop_wait time in metric profile #19881
    • Fix the wrong result of SHOW GRANTS #19834
    • Fix the incorrect query result of != ALL (subq) #19831
    • Fix a bug of converting the enum and set types #19778
    • Add a privilege check for SHOW STATS_META and SHOW STATS_BUCKET #19760
    • Fix the error of unmatched column lengths caused by builtinGreatestStringSig and builtinLeastStringSig #19758
    • If unnecessary errors or warnings occur, the vectorized control expresions fall back to their scalar execution #19749
    • Fix the error of the Apply operator when the type of the correlation column is Bit #19692
    • Fix the issue that occurs when the user queries processlist and cluster_log in MySQL 8.0 client #19690
    • Fix the issue that plans of the same type have different plan digests #19684
    • Forbid changing the column type from Decimal to Int #19682
    • Fix the issue that SELECT ... INTO OUTFILE returns the runtime error #19672
    • Fix the incorrect implementation of builtinRealIsFalseSig #19670
    • Fix the issue that the partition expression check misses the parentheses expression #19614
    • Fix a query error when there is an Apply operator upon HashJoin #19611
    • Fix an incorrect result of vectorization that casts Real as Time #19594
    • Fix the bug that the SHOW GRANTS statement shows grants for non-existent users #19588
    • Fix a query error when there is an Apply executor upon IndexLookupJoin #19566
    • Fix the wrong results when converting Apply to HashJoin on a partitioned table #19546
    • Fix incorrect results when there is an IndexLookUp executor on the inner side of an Apply #19508
    • Fix an unexpected panic when using view #19491
    • Fix the incorrect result of the anti-semi-join query #19477
    • Fix the bug that the TopN statistics is not deleted when the statistics is dropped #19465
    • Fix a wrong result caused by mistaken usage of batch point get #19460
    • Fix the bug that a column cannot be found in indexLookupJoin with a virtual generated column #19439
    • Fix an error that different plans of the select and update queries compare datum #19403
    • Fix a data race for TiFlash work index in Region cache #19362
    • Fix the bug that the logarithm function does not show a warning #19291
    • Fix an unexpected error that occurs when TiDB persists data to disks #19272
    • Support using a single partitioned table on the inner side of index join #19197
    • Fix the wrong hash key value generated for decimal #19188
    • Fix the issue that TiDB returns a no regions error when table endKey and Region endKey are the same #19895
    • Fix the unexpected success of alter partition #19891
    • Fix the wrong value of the default maximum packet length allowed for pushed down expressions #19876
    • Fix a wrong behavior for the Max/Min functions on the ENUM/SET columns #19869
    • Fix the read failure from the tiflash_segments and tiflash_tables system tables when some TiFlash nodes are offline #19748
    • Fix a wrong result of the Count(col) aggregation function #19628
    • Fix a runtime error of the TRUNCATE operation #19445
    • Fix the issue that PREPARE statement FROM @Var will fail when Var contains uppercase characters #19378
    • Fix the bug that schema charset modification in an uppercase schema will cause panic #19302
    • Fix the inconsistency of plans between information_schema.statements_summary and explain, when the information contains tikv/tiflash #19159
    • Fix the error in tests that the file does not exist for select into outfile #19725
    • Fix the issue that INFORMATION_SCHEMA.CLUSTER_HARDWARE does not have raid device information #19457
    • Make the add index operation that has a generated column with the case-when expression can exit normally when it encounters a parse error #19395
    • Fix the bug that the DDL operation takes too long to retry #19488
    • Make statements like alter table db.t1 add constraint fk foreign key (c2) references t2(c1) execute without first executing use db #19471
    • Change the dispatch error from the Error to the Info message in the server log file #19454

  • TiKV

    • Fix the estimation error for a non-index column when collation is enabled #8620
    • Fix the issue that Green GC might miss locks during the process of Region transfer #8460
    • Fix a panic issue that occurs when TiKV runs very slowly during Raft membership change #8497
    • Fix the deadlock issue that occurs between the PD client thread and other threads when calling PD sync requests #8612
    • Upgrade jemalloc to v5.2.1 to address the issue of memory allocation in huge page #8463
    • Fix the issue that the unified thread pool hangs for long-running queries #8427

  • PD

    • Add the initial-cluster-token configuration to prevent different clusters from communicating with each other during bootstrap #2922
    • Fix the unit of store limit rate when the mode is auto #2826
    • Fix the issue that some schedulers persist configuration without solving errors #2818
    • Fix the empty HTTP response in scheduler #2871 #2874

  • TiFlash

    • Fix the issue that after renaming the primary key column in previous versions, TiFlash might not start after upgrading to v4.0.4/v4.0.5
    • Fix the exceptions that occur after modifying the column's nullable attribute
    • Fix the crash caused by computing a table's replication status
    • Fix the issue that TiFlash is not available for data reads after users applied unsupported DDL operations
    • Fix the exceptions caused by unsupported collations which are treated as utf8mb4_bin
    • Fix the issue that the QPS panel for the TiFlash coprocessor executor always displays 0 in Grafana
    • Fix the wrong result of the FROM_UNIXTIME function when input is NULL

  • Tools

    • TiCDC

      • Fix the issue that TiCDC leaks memory in some cases #942
      • Fix the issue that TiCDC might panic in Kafka sink #912
      • Fix the issue that CommitTs or ResolvedTs (CRTs) might be less than resolvedTs in puller #927
      • Fix the issue that changefeed might be blocked by MySQL driver #936
      • Fix the incorrect Resolved Ts interval of TiCDC #8573

    • Backup & Restore (BR)

      • Fix a panic that might occur during checksum #479
      • Fix a panic that might occur after the change of PD Leader #496

    • Dumpling

      • Fix the issue that the NULL value for the binary type is not handled properly #137

    • TiDB Lightning

      • Fix the issue that all failed operations of writes and ingests are mistakenly displayed as successful #381
      • Fix the issue that some checkpoint updates might not be written to the database before TiDB Lightning exits #386

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