Deletion of Expired Rows
When a row expires, it is available for deletion, but it is not deleted immediately. Deletion is a background process that scans the tables for expired rows and then deletes them. Therefore, application can retrieve rows that have expired but not deleted.
By default, tables are scanned for expired rows once every hour. The frequency of the scan is governed by the expiration_scan_period property. This property is specified in seconds. If the default TTL interval for a row is short or if you want the scanner to run more frequently to delete the expired rows, set the expiration_scan_period property while creating the table. After scanning the table, all expired rows are identified and deleted. The rows that expire first are deleted first.
tibdg table create default_ttl=3600 expiration_scan_period=300 t1 key long value string