imental feature used to read historical data from a specified point in time or from a specified time range. User document, #21094 The examples of AS OF TIMESTAMP are as follows: SELECT * FROM t AS OF TIMESTAMP DDL operations might fail when rolling back due to an error #23893 – Fix the issue that the index range of the binary literal constant is incorrectly built #23672 – Fix the potential wrong results of DUPLICATE KEY UPDATE to read data from non-listed partitions #24746 – Fix the potential index out of range error when a SQL statement contains both GROUP BY and UNION #24281 – Fix the issue that the CONCAT

of unsigned flags #28254 – Fix the wrong partition pruning when the partition function is out of range #28233 – Fix the issue that planner might cache invalid plans for join in some cases #28087 – Fix to TiFlash #23907 – Fix the issue that DECIMAL overflow is missing in the %s value is out of �→ range in '%s'error message #27964 – Fix a bug that the availability detection of MPP node does not work corner cases #3118 – Fix the DATA RACE issue when assigning MPP task ID #27952 – Fix the INDEX OUT OF RANGE error for a MPP query after deleting an empty dual table #28250 – Fix the issue of false positive

easily select the right index and reduce query response time. 36 – Improve the accuracy of out-of-range estimation. For example, even if the statis- tics for a day have not been updated, TiDB can accurately Fix the data race issue of the parallel Apply operator #23280 – Fix the issue that the index out of range error is reported when sorting the IndexMerge results of the PartitionUnion operator #23919 – Fix backing off queries from TiFlash to TiKV cannot be triggered #23665 #24421 – Fix the index-out-of-range error that occurs when checking only_full_group_by �→ #23839) – Fix the issue that the result of

configuration persistence feature. The default value is ON. tidb_read_staleness �→ Newly added Controls the range of historical data that can be read in the current session. The default value is 0. tidb_regard_null_as_point Fix the issue that the REPLACE statement incorrectly changes other rows when the auto ID is out of range #30301 2.2.2 New features 2.2.2.1 SQL • TiDB supports the GBK character set since v5.4.0 Before push-down calculations, Configure the tiflash.toml file • Read historical data within a specified time range through a session variable TiDB is a multi-replica distributed database based on the Raft consensus

performance 38 in write, update, and point-query scenarios involving large values. Additionally, in Range Scan scenarios, the Titan engine’s optimization has resulted in performance comparable to that of Restore (BR) • Introduce a new integration test for Point-In-Time Recovery (PITR) in the delete range scenario, enhancing PITR stability #47738 @Leavrth • Improve the table creation performance of the issue that queries containing common table expressions (CTEs) re- port runtime error: index out of range [32] with length 32 when tidb_max_chunk_size is set to a small value #48808 @guo-shaoge • Fix the

de- fault. tidb_ �→ analyze �→ _ �→ partition �→ _ �→ concurrency �→ Modified Changes the value range from [1, �→ 18446744073709551615] �→ to [1, �→ 128] �→ . 56 Variable name Change type Description �→ opera- tors on it. 57 Variable name Change type Description tidb_ �→ opt_ �→ prefer �→ _ �→ range �→ _ �→ scan Modified Changes the default value from OFF to ON. For tables with no statis- tics (pseudo- of TiKV nodes during data import by TiDB Lightning #7853 @okJiang 86 • Rename scatter-range to scatter-range-scheduler in pd-ctl commands #8379 @okJiang • Add conflict detection for grant-hot-leader-scheduler

de- fault. tidb_ �→ analyze �→ _ �→ partition �→ _ �→ concurrency �→ Modified Changes the value range from [1, �→ 18446744073709551615] �→ to [1, �→ 128] �→ . 51 Variable name Change type Description �→ opera- tors on it. 52 Variable name Change type Description tidb_ �→ opt_ �→ prefer �→ _ �→ range �→ _ �→ scan Modified Changes the default value from OFF to ON. For tables with no statis- tics (pseudo- of TiKV nodes during data import by TiDB Lightning #7853 @okJiang 81 • Rename scatter-range to scatter-range-scheduler in pd-ctl commands #8379 @okJiang • Add conflict detection for grant-hot-leader-scheduler

intermediate results. #47275 @hawkingrei • Optimize the use of placement policies: support configuring the range of a pol- icy to global and improve the syntax support for common scenarios. #45384 @nolouch • Improve AUTO_INCREMENT columns 63 2.3.7 Partitioning Partitioning 7.5 7.1 6.5 6.1 5.4 5.3 5.2 5.1 5.0 4.0 Range partitioning Y Y Y Y Y Y Y Y Y Y Hash partitioning Y Y Y Y Y Y Y Y Y Y Key partitioning Y Y N N COALESCE PARTITION Y Y N N N N N N N N Dynamic pruning Y Y Y Y E E E E N N Range COLUMNS partitioning Y Y Y N N N N N N N Range INTERVAL partitioning Y Y E N N N N N N N Convert a partitioned table to

vari- able con- trols the num- ber of concur- rent threads during the Re- solve Locks and Delete Range steps of the Garbage Collec- tion (GC) pro- cess. Before v8.3.0, this vari- able only con- trols the Variable name Change type Description tidb_ �→ schema �→ _ �→ cache �→ _ �→ size Modified The range of values has been modi- fied to either 0 or [536870912, �→ �→ 9223372036854775807] �→ . The mini- GLOBAL scope #55022 @cfzjywxk • Improve GC (Garbage Collection) efficiency by supporting concurrent range deletion. You can control the number of concurrent threads using tidb_gc_ �→ concurrency #54570 @ekexium

after setting Regions to a larger size, TiDB introduces the concept of bucket, which is a smaller range within a Region. Using buckets as the query unit can optimize concurrent query performance when Regions changed from IN- STANCE to GLOBAL. The vari- able value per- sists to the clus- ter, and the value range is changed to [0, �→ �→ 1073741824] �→ . 43 Variable name Change type Description require_secure_transport isolation Y Y Y Y Y Y Y Y 2.3.7 Partitioning 88 Partitioning 6.1 6.0 5.4 5.3 5.2 5.1 5.0 4.0 Range partitioning Y Y Y Y Y Y Y Y Hash partitioning Y Y Y Y Y Y Y Y List partitioning Y Experimental