Re: RE: [COMMITTERS] pgsql/src/backend/access/transam ( xact.c xlog.c)

> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> >> I have to agree with Alfred here: this does not sound like a feature,
> >> it sounds like a horrid hack.  You're giving up *all* consistency
> >> guarantees for a performance gain that is really going to be pretty
> >> minimal in the WAL context.
> 
> > It does not give up consistency.  The db is still consistent, it is just
> > consistent from a few seconds ago, rather than commit time.
> 
> No, it isn't consistent.  Without the fsync you don't know what order
> the kernel will choose to plop down WAL log blocks in; you could end up
> with a corrupt log.  (Actually, perhaps that could be worked around if
> the log blocks are suitably marked so that you can tell where the last
> sequentially valid one is.  I haven't looked at the log structure in
> any detail...)

Well, WAL already has to be careful in the order it plops down the log
blocks because a single transaction can span multiple log blocks.

--  Bruce Momjian                        |  http://candle.pha.pa.us pgman@candle.pha.pa.us               |  (610)
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