> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> > My idea is that we not put UNDO information into WAL but keep a List of
> > rel ids / tuple ids in the memory of each backend and do the undo inside
> > the backend.
>
> The complaints about WAL size amount to "we don't have the disk space
> to keep track of this, for long-running transactions". If it doesn't
> fit on disk, how likely is it that it will fit in memory?
Sure, we can put on the disk if that is better. I thought the problem
with WAL undo is that you have to keep UNDO info around for all
transactions that are older than the earliest transaction. So, if I
start a nested transaction, and then sit at a prompt for 8 hours, all
WAL logs are kept for 8 hours.
We can create a WAL file for every backend, and record just the nested
transaction information. In fact, once a nested transaction finishes,
we don't need the info anymore. Certainly we don't need to flush these
to disk.
-- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (610)
853-3000+ If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill,
Pennsylvania19026