Resizing String Columns in the Destination

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When in an Event the length of an incoming string value in a Source Event Type field is larger than the size of the mapped column in the Destination, Hevo will mark the Event as Failed. For Hevo to be able to load the Event in the Destination table the column needs to be resized.

This can be done very in a single click from the Schema Mapper tab.

In the Schema Mapper tab, under options for the Event Type, click on Resize String Fields. Once this is done, Hevo will resize the required fields in the Destination table. The operation might take some time depending on the number of rows in the affected column. Success and failure notifications for the operation are sent to Slack channels (if enabled) and Activity Log.

How it works

Hevo will compare the length of the longest value encountered for a particular field with the length of the mapped Destination table column. If the length of the Destination table column is found to be shorter Hevo will resize the column. While selecting the size of the column, it uses the next larger number which is a power of 2. For example, if the maximum length seen till now is 150, then the Destination column will be resized to 256.

While resizing the column the old data is kept intact.

Once the resizing operation is complete the changes in the Destination table column size will reflect in Schema Mapper and failed Events will be replayed.


  1. This option is currently available only for Redshift and Snowflake Destination.
  2. This option is available only for varchar columns.
  3. If one of the columns to be resized is a key, then the resize operation will fail.
Last updated on 17 Mar 2021