mysql: add MySQL InnoDB link to MySQL Compatibility doc (#21131)

Author: hfxsd

mysql-compatibility.md

@@ -14,7 +14,7 @@ TiDB is highly compatible with the MySQL protocol and the common features and sy
 
 <CustomContent platform="tidb-cloud">
 
-TiDB is highly compatible with the MySQL protocol and the common features and syntax of MySQL 5.7 and MySQL 8.0. The ecosystem tools for MySQL (PHPMyAdmin, Navicat, MySQL Workbench, DBeaver and [more](https://docs.pingcap.com/tidb/v7.2/dev-guide-third-party-support#gui)) and the MySQL client can be used for TiDB.
+TiDB is highly compatible with the MySQL protocol and the common features and syntax of MySQL 5.7 and MySQL 8.0. The ecosystem tools for MySQL (PHPMyAdmin, Navicat, MySQL Workbench, DBeaver and [more](https://docs.pingcap.com/tidb/stable/dev-guide-third-party-support#gui)) and the MySQL client can be used for TiDB.
 
 </CustomContent>
 
@@ -33,15 +33,7 @@ It's important to note that TiDB does not support the MySQL replication protocol
 
 > **Note:**
 >
-> This page describes general differences between MySQL and TiDB. For more information on compatibility with MySQL in the areas of security and pessimistic transaction mode, refer to the dedicated pages on [Security](/security-compatibility-with-mysql.md) and [Pessimistic Transaction Mode](/pessimistic-transaction.md#difference-with-mysql-innodb).
-
-</CustomContent>
-
-<CustomContent platform="tidb-cloud">
-
-> **Note:**
->
-> For information about transaction differences between MySQL and TiDB, see [Pessimistic Transaction Mode](/pessimistic-transaction.md#difference-with-mysql-innodb).
+> This page describes general differences between MySQL and TiDB. For more information on compatibility with MySQL in the areas of security, see [Security Compatibility with MySQL](/security-compatibility-with-mysql.md).
 
 </CustomContent>
 
@@ -293,3 +285,7 @@ The following statements for creating, modifying, and dropping resource groups h
 - [`CREATE RESOURCE GROUP`](/sql-statements/sql-statement-create-resource-group.md)
 - [`DROP RESOURCE GROUP`](/sql-statements/sql-statement-drop-resource-group.md)
 - [`ALTER RESOURCE GROUP`](/sql-statements/sql-statement-alter-resource-group.md)
+
+## Differences on pessimistic transaction (lock) with MySQL InnoDB
+
+For differences on pessimistic transaction (lock) between TiDB and MySQL InnoDB, see [Differences from MySQL InnoDB](/pessimistic-transaction.md#differences-from-mysql-innodb).

pessimistic-transaction.md

@@ -40,7 +40,7 @@ The `BEGIN PESSIMISTIC;` and `BEGIN OPTIMISTIC;` statements take precedence over
 
 ## Behaviors
 
-Pessimistic transactions in TiDB behave similarly to those in MySQL. See the minor differences in [Difference with MySQL InnoDB](#difference-with-mysql-innodb).
+Pessimistic transactions in TiDB behave similarly to those in MySQL. See the minor differences in [Differences from MySQL InnoDB](#differences-from-mysql-innodb).
 
 - For pessimistic transactions, TiDB introduces snapshot read and current read.
 
@@ -82,7 +82,7 @@ Pessimistic transactions in TiDB behave similarly to those in MySQL. See the min
 
 - TiDB supports the `FOR UPDATE OF TABLES` syntax. For a statement that joins multiple tables, TiDB only applies pessimistic locks on the rows that are associated with the tables in `OF TABLES`.
 
-## Difference with MySQL InnoDB
+## Differences from MySQL InnoDB
 
 1. When TiDB executes DML or `SELECT FOR UPDATE` statements that use range in the WHERE clause, concurrent DML statements within the range are not blocked.
 

sql-statements/sql-statement-select.md

@@ -101,7 +101,7 @@ TableSample ::=
 |`ORDER BY` | The `ORDER BY` clause is used to sort the data in ascending or descending order, based on columns, expressions or items in the `select_expr` list.|
 |`LIMIT` | The `LIMIT` clause can be used to constrain the number of rows. `LIMIT` takes one or two numeric arguments. With one argument, the argument specifies the maximum number of rows to return, the first row to return is the first row of the table by default; with two arguments, the first argument specifies the offset of the first row to return, and the second specifies the maximum number of rows to return. TiDB also supports the `FETCH FIRST/NEXT n ROW/ROWS ONLY` syntax, which has the same effect as `LIMIT n`. You can omit `n` in this syntax and its effect is the same as `LIMIT 1`. |
 |`Window window_definition`| This is the syntax for window function, which is usually used to do some analytical computation. For more information, refer to [Window Function](/functions-and-operators/window-functions.md). |
-| `FOR UPDATE`  | The `SELECT FOR UPDATE` clause locks all the data in the result sets to detect concurrent updates from other transactions. Data that match the query conditions but do not exist in the result sets are not read-locked, such as the row data written by other transactions after the current transaction is started. When TiDB uses the [Optimistic Transaction Mode](/optimistic-transaction.md), the transaction conflicts are not detected in the statement execution phase. Therefore, the current transaction does not block other transactions from executing `UPDATE`, `DELETE` or `SELECT FOR UPDATE` like other databases such as PostgreSQL. In the committing phase, the rows read by `SELECT FOR UPDATE` are committed in two phases, which means they can also join the conflict detection. If write conflicts occur, the commit fails for all transactions that include the `SELECT FOR UPDATE` clause. If no conflict is detected, the commit succeeds. And a new version is generated for the locked rows, so that write conflicts can be detected when other uncommitted transactions are being committed later. When TiDB uses the [Pessimistic Transaction Mode](/pessimistic-transaction.md), the behavior is basically the same as other databases. Refer to [Difference with MySQL InnoDB](/pessimistic-transaction.md#difference-with-mysql-innodb) to see the details. TiDB supports the `NOWAIT` modifier for `FOR UPDATE`. See [TiDB Pessimistic Transaction Mode](/pessimistic-transaction.md#behaviors) for details. |
+| `FOR UPDATE`  | The `SELECT FOR UPDATE` clause locks all the data in the result sets to detect concurrent updates from other transactions. Data that match the query conditions but do not exist in the result sets are not read-locked, such as the row data written by other transactions after the current transaction is started. When TiDB uses the [Optimistic Transaction Mode](/optimistic-transaction.md), the transaction conflicts are not detected in the statement execution phase. Therefore, the current transaction does not block other transactions from executing `UPDATE`, `DELETE` or `SELECT FOR UPDATE` like other databases such as PostgreSQL. In the committing phase, the rows read by `SELECT FOR UPDATE` are committed in two phases, which means they can also join the conflict detection. If write conflicts occur, the commit fails for all transactions that include the `SELECT FOR UPDATE` clause. If no conflict is detected, the commit succeeds. And a new version is generated for the locked rows, so that write conflicts can be detected when other uncommitted transactions are being committed later. When TiDB uses the [Pessimistic Transaction Mode](/pessimistic-transaction.md), the behavior is basically the same as other databases. Refer to [Differences from MySQL InnoDB](/pessimistic-transaction.md#differences-from-mysql-innodb) to see the details. TiDB supports the `NOWAIT` modifier for `FOR UPDATE`. See [TiDB Pessimistic Transaction Mode](/pessimistic-transaction.md#behaviors) for details. |
 |`LOCK IN SHARE MODE` | To guarantee compatibility, TiDB parses these three modifiers, but will ignore them. |
 | `TABLESAMPLE` | To get a sample of rows from the table. |