Kbase 19754: Transaction State with PROQUIET
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
10/10/2008 |
|
Status: Unverified
GOAL:
Additional detail regarding "in-flight" and "active" transactions when using PROQUIET
FIX:
Memory-resident buffers /are/ flushed to disk but there may be in-flight transactions. A backup taken during the quiet point via mirror splitting is similar to a Progress online backup. It is an image of the database at that moment in time. It looks as if the system crashed at that instant.
If restoring a quiet point backup, the in-flight transactions will be rolled back when you restart the database and the database goes through recovery.
The terms "in-flight transaction" and "active transaction" can be used interchangeably. Meaning that a transaction that has not yet committed (completed). The database changes made by that transaction would normally have been made in memory (in the database buffer pool) but not necessarily written to disk.
The quiet point does flush those changes to disk.
Furthermore, since the transaction has not committed, it can still make further changes to the database later and it could decide either to roll back or commit at some time in the future.
The bi and ai notes /have/ been generated for /all/ changes made by active (not committed) transactions. The changed database blocks may be in memory or on disk.
All the data in memory is flushed to disk. What the backup does not have is anything that is not yet changed, and anything that is removed when the backup is opened and active transactions are rolled back.