Data Versioning

Detect updates and prevent data loss with versioning

Every Glide Big Table has a version number that increases whenever its data changes. Additionally, each row in a Big Table keeps track of the table version when it was last modified. This information can be used to detect changes to data and prevent mid-air collisions that can result in data loss.

Getting the Current Version

Most API endpoints that work with Big Tables return the current version of the table in the ETag response header.

If you only want to get the current version of a table without performing any other operation, use the Get Rows Version endpoint. You can poll this endpoint to detect changes to the table.

Preventing Data Loss

When updating data in a Big Table, you can specify the version of the table you expect to be working with using the If-Match header. How this value is interpreted depends on the endpoint:

• The Overwrite Table endpoint rejects the request if the current table version is newer than the version specified in the If-Match header.
• The Update Row endpoint rejects the request if the row has been modified since the version specified in the If-Match header. The update is still allowed if another row in the table was modified since the specified version.

In both cases, an HTTP 412 Precondition Failed response is returned if the condition is not met.