Re: [Bizgres-general] WAL bypass for INSERT, UPDATE and

Andrew Dunstan wrote:
> >>My concern is more about making plain that this is for special operations,
> >>not normal operations. Or maybe I have misunderstood the purpose.
> >>
> >>
> >
> >Rephrase that as "full ownership rights must be obtained to load data in
> >a way that requires dropping any existing indexes and locking out other
> >users of the table". I don't think the use-case for this will be very
> >large for non-owners, or indeed even for owners except during initial
> >table creation; and so I don't think the above argument is strong.
> >
> >
> >
> >
>
> Those restrictions aren't true of Bruce's proposed drop and
> delete/truncate recovery modes, are they?

Only the owner could do the ALTER, for sure, but once the owner sets it,
any user with permission to write to the table would have those
characteristics.

> People do crazy things in pursuit of performance. Illustration: a few
> months ago I was instrumenting an app (based on MySQL/ISAM) and I
> noticed that under load it simply didn't update the inventory properly -
> of 1000 orders placed within a few seconds it might reduce inventory by
> 3 or 4. I reported this and they shrugged their shoulders and said
> "well, we'd have to lock the table and that would slow everything down
> ...".
>
> I just want to be sure we aren't providing a footgun. "Oh, just set
> recovery mode to delete. It won't make any difference unless you crash
> and you'll run faster."

I think we have to trust the object owner in this case. I don't know of
any super-user-only ALTER commands, but I suppose we could set it up
that way if we wanted.

--
Bruce Momjian | http://candle.pha.pa.us
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