Kbase 19808: V9 Database Manager Handles Transactions
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
29/05/2002 |
|
Solution ID: 19808
GOAL:
V9 Database Manager Handles Transactions
FACT(s) (Environment):
Progress 9.x
CAUSE:
Beginning with Progress Version 9.x, the database manager handles transaction begin differently than in previous releases. The Version 9.x database manager does not write a transaction begin note at the start of the transaction, instead the writing is delayed until some database change is made by the transaction itself.
If transaction begin finishes without changing anything, no transaction end note is written.
FIX:
This change has several beneficial effects:
- Before Image (BI) file cluster reuse is improved because transactions that have just finished reading data do not use any BI space and transactions that do read data now write to the BI log later and span a smaller number of clusters.
- A slight reduction in BI log space consumption.
- A slight gain in performance due to the elimination of some BI writes.
- A slight gain in concurrency during transaction start, that produces a minor performance gain.
- A slight gain in concurrency during transaction end for transactions that did not change the database, resulting in another minor performance gain.
All this is internal optimization to the database transaction manager and is invisible at the application level. To an application, everthing appears to work the same, just better.
The transactions are still logged under PROMON, but not written to the BI and After Image (AI) files until the data is modified. Transaction table entry and transaction ID allocation are completed but the notes are delayed.