Expected values generated from sequence are missing

Expected values are missing in newly created records where field values are generated from a sequence.

A set of database records is created in which on field value is generated from a sequence. When set of records is then transmitted to a target database, the sequence values are checked to make sure no data was lost during the transmission. Occasionally, some values from the sequence are missing in the set of transmitted records on the target database. When the source database is checked, the same values are found to be missing from the source database as well.

One or more transaction backout entries are found in the database log.

This is expected behavior. The current value of a sequence is not rolled back when database records in which the sequence was used are backed out of the database during a transaction rollback.The relevant field in next new record will be assigned the current value of the sequence, which is whatever it was before the transaction rollback occurred. The values used in the backed-out records are not seen in the database once the rollback is completed.

If missing values are noticed in a set of records containing values assigned from a sequence, check the database log for messages (2252) and (2253) during the relevant time frame to see if a rolled-back transaction accounts for the gap.

References to Other Documentation:

OpenEdge Getting Started: ABL Essentials, "Managing Transactions : Controlling the size of a transaction : The NO-UNDO keyword on temp-tables and variables"
https://documentation.progress.com/output/ua/OpenEdge_latest/index.html#page/gsabl%2Fthe-no-undo-keyword-on-temp-tables-and-variables.html%23

Progress Articles:

 Are database sequences part of database transactions?