Fix the

When you run an SQL statement on a MySQL database in DMS, the error "Row size too large" is returned because the total row size exceeds the 65,535-byte limit. To fix this, convert large columns to TEXT or BLOB, or shorten their length.

Problem description

When you run an SQL statement on an ApsaraDB RDS for MySQL or self-managed MySQL database in the DMS console, the following error is returned. A self-managed database can be deployed on an ECS instance or in an Internet Data Center (IDC).

Row size too large. The maximum row size for the used table type, not counting BLOBs, is 65535. This includes storage overhead, check the manual. You have to change some columns to TEXT or BLOBs

Cause

MySQL enforces a 65,535-byte limit on the total row size, regardless of the storage engine. Even if InnoDB supports larger rows, this limit still applies. MySQL: Limits on Table Column Count and Row Size.

Solutions

Use one of the following methods:

Change large VARCHAR or CHAR columns to TEXT or BLOB.
1. Log on to the DMS console.
2. In the left-side navigation pane, expand the database instance and click the target database.
3. On the SQL Console page, right-click the target table and select Edit Table Schema.
4. On the Edit Table page, click the Column Information tab and change the column type to TEXT or BLOB.
Shorten the length of large VARCHAR or CHAR columns.
1. Log on to the DMS console.
2. In the left-side navigation pane, expand the database instance and click the target database.
3. On the SQL Console page, right-click the target table and select Edit Table Schema.
4. On the Edit Table page, click the Column Information tab and reduce the column length.

Applicable to

Data Management (DMS)
ApsaraDB RDS