Error: Row Size Too Large

Issue

Syncs fail with the following error:

Row size too large (> 8126). Changing some columns to TEXT or BLOB may help. In current row format, BLOB prefix of 0 bytes is stored inline.

Environment

Connector: MySQL

Resolution

To resolve this issue, do the following:

1. In Fivetran, go to your MySQL connection page.
2. In the top right corner, set the Enabled toggle to OFF to pause the connection.
3. Select the Schema tab.
4. Identify unnecessary columns that may significantly increase row size, such as large text, binary, or JSON columns, then deselect them to exclude them from the sync.
5. Click Save changes.
6. Re-enable the connection by setting the Enabled toggle to ON.
7. Wait for the sync to run again, or click Sync in the top right.

Cause

This issue occurs when the combined size of a row exceeds the MySQL InnoDB row size limit of 8,126 bytes. The error is caused by the total row size, not necessarily by a single column.

MySQL enforces this limit at the database level. As a result, Fivetran cannot sync records where the combined column data exceeds the maximum supported row size. Sync logs do not identify which columns contribute most to the row size. For more information, see the MySQL InnoDB Limits documentation.