diff --git a/mysql-compatibility.md b/mysql-compatibility.md index 057d1ed968434..b0df8e2110acd 100644 --- a/mysql-compatibility.md +++ b/mysql-compatibility.md @@ -11,7 +11,7 @@ TiDB supports both the MySQL wire protocol and the majority of its syntax. This Currently TiDB Server advertises itself as MySQL 5.7 and works with most MySQL database tools such as PHPMyAdmin, Navicat, MySQL Workbench, mysqldump, and Mydumper/myloader. -However, TiDB does not support some of MySQL features or behaves differently from MySQL because these features cannot be easily implemented in a distributed system. For some MySQL syntax, TiDB can parse but does not process it. For example, the `ENGINE` table option in the `CREATE TABLE` statement can be parsed but is ignored. +However, some features of MySQL are not supported. This could be because there is now a better way to solve the problem (such as XML functions superceded by JSON), or a lack of current demand versus effort required (such as stored procedures and functions). Some features might also be difficult to implement as a distributed system. > **Note:** > @@ -187,11 +187,11 @@ Architecturally, TiDB does support a similar storage engine abstraction to MySQL ### SQL modes -TiDB supports **all of the SQL modes** from MySQL 5.7 with minor exceptions: +TiDB supports most [SQL modes](/sql-mode.md): -- The compatibility modes deprecated in MySQL 5.7 and removed in MySQL 8.0 are not supported (such as `ORACLE`, `POSTGRESQL` etc). -- The mode `ONLY_FULL_GROUP_BY` has minor [semantic differences](/functions-and-operators/aggregate-group-by-functions.md#differences-from-mysql) to MySQL 5.7, which we plan to address in the future. -- The SQL modes `NO_DIR_IN_CREATE` and `NO_ENGINE_SUBSTITUTION` are supported for compatibility, but are not applicable to TiDB. +- The compatibility modes, such as `ORACLE` and `POSTGRESQL` are parsed but ignored. Compatibility modes are deprecated in MySQL 5.7 and removed in MySQL 8.0. +- The `ONLY_FULL_GROUP_BY` mode has minor [semantic differences](/functions-and-operators/aggregate-group-by-functions.md#differences-from-mysql) from MySQL 5.7. +- The `NO_DIR_IN_CREATE` and `NO_ENGINE_SUBSTITUTION` SQL modes in MySQL are accepted for compatibility, but are not applicable to TiDB. ### Version-specific comments diff --git a/sql-mode.md b/sql-mode.md index 3d7e005468627..6edaa673978ee 100644 --- a/sql-mode.md +++ b/sql-mode.md @@ -49,12 +49,12 @@ Ensure that you have `SUPER` privilege when setting SQL mode at `GLOBAL` level, | `NO_ENGINE_SUBSTITUTION` | Prevents the automatic replacement of storage engines if the required storage engine is disabled or not compiled. (syntax support only)| | `PAD_CHAR_TO_FULL_LENGTH` | If this mode is enabled, the system does not trim the trailing spaces for `CHAR` types. (full support) | | `REAL_AS_FLOAT` | Treats `REAL` as the synonym of `FLOAT`, not the synonym of `DOUBLE` (full support)| -| `POSTGRESQL` | Equivalent to `PIPES_AS_CONCAT`, `ANSI_QUOTES`, `IGNORE_SPACE`, `NO_KEY_OPTIONS`, `NO_TABLE_OPTIONS`, `NO_FIELD_OPTIONS` (full support)| -| `MSSQL` | Equivalent to `PIPES_AS_CONCAT`, `ANSI_QUOTES`, `IGNORE_SPACE`, `NO_KEY_OPTIONS`, `NO_TABLE_OPTIONS`, `NO_FIELD_OPTIONS` (full support)| -| `DB2` | Equivalent to `PIPES_AS_CONCAT`, `ANSI_QUOTES`, `IGNORE_SPACE`, `NO_KEY_OPTIONS`, `NO_TABLE_OPTIONS`, `NO_FIELD_OPTIONS` (full support)| +| `POSTGRESQL` | Equivalent to `PIPES_AS_CONCAT`, `ANSI_QUOTES`, `IGNORE_SPACE`, `NO_KEY_OPTIONS`, `NO_TABLE_OPTIONS`, `NO_FIELD_OPTIONS` (syntax support only)| +| `MSSQL` | Equivalent to `PIPES_AS_CONCAT`, `ANSI_QUOTES`, `IGNORE_SPACE`, `NO_KEY_OPTIONS`, `NO_TABLE_OPTIONS`, `NO_FIELD_OPTIONS` (syntax support only)| +| `DB2` | Equivalent to `PIPES_AS_CONCAT`, `ANSI_QUOTES`, `IGNORE_SPACE`, `NO_KEY_OPTIONS`, `NO_TABLE_OPTIONS`, `NO_FIELD_OPTIONS` (syntax support only)| | `MAXDB` | Equivalent to `PIPES_AS_CONCAT`, `ANSI_QUOTES`, `IGNORE_SPACE`, `NO_KEY_OPTIONS`, `NO_TABLE_OPTIONS`, `NO_FIELD_OPTIONS`, `NO_AUTO_CREATE_USER` (full support)| -| `MySQL323` | Equivalent to `NO_FIELD_OPTIONS`, `HIGH_NOT_PRECEDENCE` (full support)| -| `MYSQL40` | Equivalent to `NO_FIELD_OPTIONS`, `HIGH_NOT_PRECEDENCE` (full support)| -| `ANSI` | Equivalent to `REAL_AS_FLOAT`, `PIPES_AS_CONCAT`, `ANSI_QUOTES`, `IGNORE_SPACE` (full support)| -| `TRADITIONAL` | Equivalent to `STRICT_TRANS_TABLES`, `STRICT_ALL_TABLES`, `NO_ZERO_IN_DATE`, `NO_ZERO_DATE`, `ERROR_FOR_DIVISION_BY_ZERO`, `NO_AUTO_CREATE_USER` (full support) | -| `ORACLE` | Equivalent to `PIPES_AS_CONCAT`, `ANSI_QUOTES`, `IGNORE_SPACE`, `NO_KEY_OPTIONS`, `NO_TABLE_OPTIONS`, `NO_FIELD_OPTIONS`, `NO_AUTO_CREATE_USER` (full support)| +| `MySQL323` | Equivalent to `NO_FIELD_OPTIONS`, `HIGH_NOT_PRECEDENCE` (syntax support only)| +| `MYSQL40` | Equivalent to `NO_FIELD_OPTIONS`, `HIGH_NOT_PRECEDENCE` (syntax support only)| +| `ANSI` | Equivalent to `REAL_AS_FLOAT`, `PIPES_AS_CONCAT`, `ANSI_QUOTES`, `IGNORE_SPACE` (syntax support only)| +| `TRADITIONAL` | Equivalent to `STRICT_TRANS_TABLES`, `STRICT_ALL_TABLES`, `NO_ZERO_IN_DATE`, `NO_ZERO_DATE`, `ERROR_FOR_DIVISION_BY_ZERO`, `NO_AUTO_CREATE_USER` (syntax support only) | +| `ORACLE` | Equivalent to `PIPES_AS_CONCAT`, `ANSI_QUOTES`, `IGNORE_SPACE`, `NO_KEY_OPTIONS`, `NO_TABLE_OPTIONS`, `NO_FIELD_OPTIONS`, `NO_AUTO_CREATE_USER` (syntax support only)|