Maintaining a Table

Scenarios

While working with MySQL databases, you do a lot of changes such as data insert, update, and deletion, which may cause table fragmentation. As a result, the database server performance is deteriorated. To handle this, periodic maintenance is required.

Functions

• Check

  The CHECK TABLE statement adds a read-only lock to the table.

  Allows you to check whether there are errors in database tables using the CHECK TABLE statement. You can check a table with any of the following methods:

  • General: Scan rows to verify that deleted links are valid. Alternatively, calculate a key checksum for the rows and verifies the validity using the obtained checksum.
  • Fast: Check only tables that have not been closed properly.
  • Quick: Do not scan rows or check for incorrect links.
  • Changed: Check only tables that have been changed since the last check or tables that have not been closed properly.
  • Extended: Search for keywords in each row. This ensures that the table is 100% consistent, but takes a long time.
• Repair

  Allows you to use the REPAIR TABLE statement to repair possibly corrupted or incorrect tables. You can repair tables using any of the following three methods:

  • Check: a simple repair, which repairs data and index files.
  • Quick: the quickest repair, which repairs only index files, but not data files.
  • Extended: the slowest repair, which creates indexes row by row to repair data and index files.

Procedure

The following uses the Check operation as an example to explain how to maintain tables.

1. On the top menu bar, choose Database Management.
2. On the displayed Objects page, select Tables, locate the target table, and choose More > Maintain > Check > Check in the Operation column.
3. In the displayed dialog box, click Yes.