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TiDB 2.0.9 Release Notes

On November 19, 2018, TiDB 2.0.9 is released. Compared with TiDB 2.0.8, this release has great improvement in system compatibility and stability.


  • Fix the issue caused by the empty statistics histogram #7927
  • Fix the panic issue of the UNION ALL statement in some cases #7942
  • Fix the stack overflow issue caused by wrong DDL Jobs #7959
  • Add the slow log for the Commit operation #7983
  • Fix the panic issue caused by the too large Limit value #8004
  • Support specifying the utf8mb4 character set in the USING clause #8048
  • Make the TRUNCATE built-in function support parameters of unsigned integer type #8069
  • Fix the selectivity estimation issue of the primary key for the statistics module in some cases #8150
  • Add the Session variable to control whether _tidb_rowid is allowed to be written in #8126
  • Fix the panic issue of PhysicalProjection in some cases #8154
  • Fix the unstable results of the Union statement in some cases #8168
  • Fix the issue that NULL is not returned by values in the non-Insert statement #8179
  • Fix the issue that the statistics module cannot clear the outdated data in some cases #8184
  • Make the maximum allowed running time for a transaction a configurable option #8209
  • Fix the wrong comparison algorithm of expression rewriter in some cases #8288
  • Eliminate the extra columns generated by the UNION ORDER BY statement #8307
  • Support the admin show next_row_id statement #8274
  • Fix the escape issue of special characters in the Show Create Table statement #8321
  • Fix the unexpected errors in the UNION statement in some cases #8318
  • Fix the issue that canceling a DDL job causes no rollback of a schema in some cases #8312
  • Change tidb_max_chunk_size to a global variable #8333
  • Add an upper bound to the Scan command of ticlient, to avoid overbound scan #8309 #8310


  • Fix the issue that the PD server gets stuck caused by etcd startup failure #1267
  • Fix the issues related to pd-ctl reading the Region key #1298 #1299 #1308
  • Fix the issue that the regions/check API returns the wrong result #1311
  • Fix the issue that PD cannot restart join after a PD join failure #1279


  • Add the end-key limit to the kv_scan interface #3749
  • Abandon the max-tasks-xxx configuration and add max-tasks-per-worker-xxx #3093
  • Fix the CompactFiles issue in RocksDB #3789
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