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tidb-server v4.0.0-beta
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@bb7133 bb7133 released this 13 May 02:58
v4.0.0-beta
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Learn about vigilant mode.

Improvements

  • Increase the accuracy of calculating the cost of Index Join by considering the row counts of both driving tables and driven tables #12085
  • Improve the performance when the columns involved in a query can be fully covered by indexes #12022
  • Improve the performance of table query by supporting the Index Merge feature #10121 #10512 #11245 #12225 #12248 #12305 #12843
  • Improve the performance of Range calculation and reduce the CPU overhead by caching index results and eliminating duplicate results #12856
  • Decouple the level of slow logs from the level of ordinary logs #12359
  • Increase the default value of the query-log-max-len parameter to 4096 to reduce the number of truncated SQL outputs. This parameter can be adjusted dynamically. #12491
  • Convert a narrow data range of the discrete type into point set and use CMSketch to improve the estimation accuracy when estimating the number of rows #11524
  • Extract the TopN information from CMSketch for normal Analyze and separately maintain the frequently occurring values #11409
  • Support dynamically adjusting the depth and width of CMSketch and the number of TopN information #11278
  • Support automatically capturing and evolving SQL Binding #13199
  • Optimize the encoding format of communication with TiKV by using Chunk to improve communication performance #12023 #12536 #12613 #12621 #12899 #13060 #13349
  • Support the new row store format to improve the performance of the wide table #12634
  • Improve the stability of Kill #10841
  • Improve the performance of IndexLookupJoin and reduce memory consumption during execution by splitting IndexLookupJoin into IndexHashJoin and IndexMergeJoin #8861 #12139 #12349 #13238 #13451 #13714
  • Output the detailed backoff information of TiKV RPC in the slow log to facilitate troubleshooting #13770
  • Optimize and unify the format of the memory statistics in the expensive log #12809
  • Optimize the explicit format of EXPLAIN and support outputting information about the operator’s usage of memory and disk
  • Optimize the check for duplicate values in LOAD DATA based on the transaction size and support setting the transaction size by configuring the tidb_dml_batch_size parameter #11132
  • Optimize the Recover Binlog interface to ensure waiting all transactions to be committed before returning to the client #13740
  • Optimize the performance of LOAD DATA by separating the data preparing routine and the commit routine and assigning the workload to different Workers #11533 #11284

New Features

  • Support using the LIKE or WHERE clause in ADMIN SHOW DDL JOBS for conditional filtering #12484
  • Add the TIDB_ROW_ID_SHARDING_INFO column in the information_schema.tables table to output the RowID scattering information (for example, the value of the SHARD_ROW_ID_BITS column in table A is "SHARD_BITS={bit_number}") #13418
  • Add the oom-use-tmp-storage parameter (true by default) to control whether to use temporary files to cache intermediate results when the memory usage for the execution of a single SQL statement exceeds mem-quota-query and the SQL contains Hash Join #11832 #11937 #12116 #12067
  • Support querying the binlog statuses enabled by TiDB servers in the cluster through the HTTP info/all interface #13025
  • Support adding the AutoRandom keyword in the column attribute to control whether the system automatically assigns a random integer to the primary key, which avoids the hotspot problem caused by the AUTO_INCREMENT primary key #13127
  • Support Table Locks #11038
  • Support the MySQL-compatible Read Committed transaction isolation level when using the pessimistic transaction mode #14087
  • Support large-sized transactions. The transaction size is limited by the size of the physical memory.
  • Support hexadecimal and binary expressions as separators in LOAD DATA #11029 #13914 #13692 #13686 #11415 #13927 #13764 #13720
  • Add 15 SQL hints to control the behavior of the optimizer and make the optimizer more stable

Changed Behaviors

Bugfix

Assets 2