. . . . . . . . . . . . . . . . . . . . . . . . . . . 31 3.4.4. Operations Using Date and Time Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 3.5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235 6.2.1. INSERT … VALUES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237 6.2.3. INSERT … DEFAULT VALUES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . 40 Table of Contents 2 3.4.6. Operations Using Date and Time Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 3.4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316 6.2.1. INSERT … VALUES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 318 6.2.3. INSERT … DEFAULT VALUES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

• Hint Sharding Strategy HintShardingStrategy refers to the sharding strategy which get sharding values by hint rather than extracted from SQL. • None sharding strategy NoneShardingStrategy refers to ShardingSphere can be compatible with SQL in way of parsing SQL statements and extracting columns and values to shard. If SQL does not have sharding conditions, it is impossible to shard without full route Hint in ShardingSphere. Mechanism Apache ShardingSphere uses ThreadLocal to manage sharding key values. Users can program to add sharding conditions to HintManager, but the condition is only effective

creation_date) values (1, 1, ‘insert’, ‘2017‐08‐08’), (2, 2, ‘insert’, ‘2017‐08‐08’) ON DUPLICATE KEY UPDATE status = ‘init’; INSERT INTO t_order_item (order_id , user_id , sta‐ tus , creation_date)VALUES status = conv ert(to_base64(aes_encrypt(1, ‘key’)) USING utf8) ON DUPLICATE KEY UPDATE status = VALUES(status); INSERT INTO t_order SET order_id = 1, user_id = 1, status = CON‐ VERT(to_base64(aes_encrypt(1 t_order (`field1`, `field2`) VALUES (10, 1); 可以看到，上述 SQL 中并未包含自增主键，是需要数据库自行填充的。ShardingSphere 配置自增主键后， SQL 将改写为： INSERT INTO t_order (`field1`, `field2`, order_id) VALUES (10, 1, xxxxx); 改写后的 SQL 将在

old-value- �→ cache- �→ memory- �→ quota Newly added Sets the upper limit of memory usage by TiCDC old values. The default value is 512MB. TiKV con- figuration file sink- �→ memory- �→ quota Newly added Sets projection result is empty #23887 – Fix the issue of wrong query results when a column contains NULL values in some cases #23891 – Forbid generating MPP plans when the scan contains virtual columns #23886 up after the file dictionary file is damaged #9886 – Fix a TiCDC OOM issue caused by reading old values #9996 #9981 – Fix the issue of empty value in the secondary index for the clustered primary key column

in the configuration file before the �→ upgrade already exist, TiDB will automatically update the values of �→ the configured items to those of the corresponding system variables �→ during the upgrade process the foundation for implementing Change Data Capture and incremental backup and restore. • Data is scoped according to different usage and supports co-existence of a single TiDB cluster, Transactional KV clusters inherit the configuration from the configuration file. New clusters use the new default values, which means Prepared Plan Cache is enabled by default and each session can cache 100 plans at most

multiple TiDB servers or allocated sequentially. It is recommended that you do not mix default values and custom values. Otherwise, you might encounter the Duplicated Error error message. • You can use the TABLE t(id INT UNIQUE KEY AUTO_INCREMENT); Query OK, 0 rows affected (0.05 sec) mysql> INSERT INTO t VALUES(),(),(); Query OK, 3 rows affected (0.00 sec) Records: 3 Duplicates: 0 Warnings: 0 mysql> SELECT ZEROFILL attribute. MySQL 8.0 deprecates this feature, and it is recommended to instead pad numeric values in your application. 2.7 TiDB Limitations This document describes the common usage limitations

issue that might occur when the Date_Format function is called with the STRING type argument and NULL values • Tools – TiCDC * Fix a bug that TiCDC owner exits abnormally when refreshing the checkpoint multiple TiDB servers or allocated sequentially. It is recommended that you do not mix default values and custom values. Otherwise, you might encounter the Duplicated Error error message. • You can use the TABLE t(id INT UNIQUE KEY AUTO_INCREMENT); Query OK, 0 rows affected (0.05 sec) mysql> INSERT INTO t VALUES(),(),(); Query OK, 3 rows affected (0.00 sec) Records: 3 Duplicates: 0 Warnings: 0 mysql> SELECT

Lightning stops reading source data and writing temporary files. Instead, 41 it writes the sorted key-values to TiKV first, and then continues the import process after TiDB Lightning deletes the local temporary packet” 2.4.2 Features that are different from MySQL 2.4.2.1 Auto-increment ID • In TiDB, the values (IDs) of an auto-incremental column are globally unique. They are incremental on a single TiDB server are not necessarily allocated sequentially. It is recommended that you do not mix default values and custom values. Otherwise, you might encounter the Duplicated Error error message. • You can use the

engine automatically segregates large values exceeding 32 KB from RocksDB’s LSM Tree, and stores them separately in Titan to optimize the handling of large values. The Titan engine is completely compatible effect, but also enhances 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 Description TiKV blob- �→ file �→ - �→ compression �→ Modified The algo- rithm used for com- pressing values in Titan, which takes value as the unit. Starting from TiDB v7.6.0, the default compres- sion algo-