Tom Lane wrote:
> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> > Do we want UNDO just for subtransactions?
> > That was pretty easily defeated, though I made an argument that you
> > could do UNDO pretty cheaply when you have WAL ensuring crash recovery.
>
> That argument was what got us into the early-7.1 WAL bloat problems.
> I don't think it's "pretty cheap" to have to hold the entire WAL for the
> length of your longest-running transactions.
With my idea, you wouldn't have to keep WAL around. Each backend would
keep a list of tids or the relid (if lots of rows are changed) in local
memory and UNDO on subtransaction abort.
-- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (610)
359-1001+ If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square,
Pennsylvania19073
