GTT State Persistence Across Db2 LUW Backup Restoration and Hibernate JOIN FETCH Pagination Interaction

GTT Behavior During Backup Restoration

IBM Db2 LUW global temporary tables (GTTs) exhibit distinct persistence characteristics that may impact application behavior following backup restoration. The research indicates GTTs are session-scoped or transaction-scoped, with session-scoped tables persisting for the connection lifetime but being lost during database restart or connection loss.

During backup restoration, GTT definitions and data are not preserved, requiring recreation of temporary table structures post-restore. This creates a potential inconsistency window where applications expecting GTT availability may fail or exhibit unexpected behavior. The timing of backup restoration relative to active transactions and sessions becomes critical for maintaining application state continuity.

Hibernate Pagination Interaction

When Hibernate executes queries with JOIN FETCH combined with setFirstResult/setMaxResults, it triggers in-memory pagination rather than database-level LIMIT/OFFSET. This behavior can cause memory exhaustion when processing large datasets, particularly problematic when GTT data needs to be restored and processed in paginated fashion.

Unresolved Decision

The interaction between GTT state loss during backup restoration and Hibernate's in-memory pagination for JOIN FETCH queries creates uncertainty about optimal recovery strategies. Key questions remain about whether applications should implement GTT recreation logic post-backup-restore, how to handle pagination memory constraints during recovery, and whether alternative temporary storage mechanisms would provide better resilience.

• Should applications implement explicit GTT recreation logic following database backup restoration?
• How can Hibernate pagination be configured to avoid in-memory processing when GTT data is restored?
• What alternative temporary storage patterns provide better backup/restore resilience in Db2 LUW environments?