| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
| Cc: | Alfred Perlstein <bright(at)wintelcom(dot)net>, Tatsuo Ishii <t-ishii(at)sra(dot)co(dot)jp>, vmikheev(at)SECTORBASE(dot)COM, peter_e(at)gmx(dot)net, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: RE: [COMMITTERS] pgsql/src/backend/access/transam ( xact.c xlog.c) |
| Date: | 2000-11-11 20:02:47 |
| Message-ID: | 28706.973972967@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)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...)
regards, tom lane
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