Merges and Point-in-Time Queries
When a merge occurs, it deletes all fragments from the stands being merged that have a system timestamp older than the configured merge timestamp (unless the merge timestamp is set to 0, in which case it will delete all fragments older than the current timestamp). This can keep multiple versions of some fragments in the database. You can query the older fragments using point-in-time queries. For details, see the Point-in-Time Queries in the Application Developer’s Guide.