[FLINK-36784][docs][pipeline-connector/mysql] Add op_ts metadata docs…

docs/content.zh/docs/connectors/pipeline-connectors/mysql.md

@@ -312,6 +312,15 @@ pipeline:
       <td>Boolean</td>
       <td>是否将TINYINT(1)类型当做Boolean类型处理，默认true。</td>
     </tr>
+    <tr>
+      <td>metadata.list</td>
+      <td>optional</td>
+      <td style="word-wrap: break-word;">false</td>
+      <td>String</td>
+      <td>
+        可额外读取的SourceRecord中元数据的列表，后续可直接使用在transform模块，英文逗号 `,` 分割。目前可用值包含：op_ts。
+      </td>
+    </tr>
     </tbody>
 </table>
 </div>

docs/content.zh/docs/core-concept/transform.md

@@ -70,6 +70,29 @@ There are some hidden columns used to access metadata information. They will onl
 | __table_name__      | String    | Name of the table that contains the row.     |
 | __data_event_type__ | String    | Operation type of data change event.         |
 
+除了以上的元数据字段，连接器也可以解析额外的元数据并放入 DataChangeEvent 的 meta map中，这些元数据也可以在transform使用。
+例如如下的作业，MySQL 连接器可以解析 `op_ts` 元数据并在transform中使用。
+
+```yaml
+source:
+  type: mysql
+  hostname: localhost
+  port: 3306
+  username: testuser
+  password: testpwd
+  tables: testdb.customer
+  server-id: 5400-5404
+  server-time-zone: UTC
+  metadata.list: op_ts
+
+transform:
+  - source-table: testdb.customer
+    projection: \*, __namespace_name__ || '.' || __schema_name__ || '.' || __table_name__ AS identifier_name, __data_event_type__ AS type, op_ts AS opts
+
+sink:
+  type: values
+```
+
 ## Metadata relationship
 
 | Type                 | Namespace | SchemaName | Table |

docs/content/docs/connectors/pipeline-connectors/mysql.md

@@ -332,6 +332,15 @@ pipeline:
           When 'use.legacy.json.format' = 'false', the data would be converted to {"key1": "value1", "key2": "value2"}, with whitespace before values and after commas preserved.
       </td>
     </tr>
+    <tr>
+      <td>metadata.list</td>
+      <td>optional</td>
+      <td style="word-wrap: break-word;">false</td>
+      <td>String</td>
+      <td>
+        List of readable metadata from SourceRecord to be passed to downstream and could be used in transform module, split by `,`. Available readable metadata are: op_ts.
+      </td>
+    </tr>
     </tbody>
 </table>
 </div>

docs/content/docs/core-concept/transform.md

@@ -70,6 +70,30 @@ There are some hidden columns used to access metadata information. They will onl
 | __table_name__      | String    | Name of the table that contains the row.     |
 | __data_event_type__ | String    | Operation type of data change event.         |
 
+Besides these fields, pipeline connectors could parse more metadata and put them in the meta map of the DataChangeEvent.
+These metadata could be accessed in the transform module.
+For example, MySQL pipeline connector could parse `op_ts` and use it in the transform module.
+
+```yaml
+source:
+  type: mysql
+  hostname: localhost
+  port: 3306
+  username: testuser
+  password: testpwd
+  tables: testdb.customer
+  server-id: 5400-5404
+  server-time-zone: UTC
+  metadata.list: op_ts
+
+transform:
+  - source-table: testdb.customer
+    projection: \*, __namespace_name__ || '.' || __schema_name__ || '.' || __table_name__ AS identifier_name, __data_event_type__ AS type, op_ts AS opts
+
+sink:
+  type: values
+```
+
 ## Metadata relationship
 
 | Type                 | Namespace | SchemaName | Table |