Re: Persistent changes in rolled-back transactions
| От | Wael Khobalatte |
|---|---|
| Тема | Re: Persistent changes in rolled-back transactions |
| Дата | |
| Msg-id | CAJZ8yobSeSs8b28jzH5P4=OGvntPNxPyu_PsNWKm4De2E_WTjg@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: Persistent changes in rolled-back transactions ("David G. Johnston" <david.g.johnston@gmail.com>) |
| Ответы |
Re: Persistent changes in rolled-back transactions
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| Список | pgsql-admin |
> Why do you say truncate is non-transactional? Something simple proves that it's not?
Right, I meant 'non-transactional' in the sense that "persisted changes" as you quoted them will also appear in the case of Truncate (MVCC-safety is more correct here). As David mention I also thought it was not transactional at all, but it seems it is in recent version or I am seeing ghosts. Regardless, it's definitely fits the description of what you are trying to be aware of when it comes to transactional behavior.
Consider starting a transaction in REPEATABLE READ, do a "begin", then nothing (because if you select you block the upcoming truncate). In a different session, do the truncation, commit it. Back to the REPEATABLE READ transaction, still open, you select, the data is gone. Therefore "persisted changes" is true.
Right, I meant 'non-transactional' in the sense that "persisted changes" as you quoted them will also appear in the case of Truncate (MVCC-safety is more correct here). As David mention I also thought it was not transactional at all, but it seems it is in recent version or I am seeing ghosts. Regardless, it's definitely fits the description of what you are trying to be aware of when it comes to transactional behavior.
Consider starting a transaction in REPEATABLE READ, do a "begin", then nothing (because if you select you block the upcoming truncate). In a different session, do the truncation, commit it. Back to the REPEATABLE READ transaction, still open, you select, the data is gone. Therefore "persisted changes" is true.
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