Re: NO WAIT ...

Tom Lane wrote:
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > I imagine folks would want it on UPDATE, DELETE, and VACUUM FULL too,
>
> Why? You can do a SELECT FOR UPDATE first and then you know that you
> have the row lock. There's no need for any special handling of UPDATE
> or DELETE. I don't see the applicability to VACUUM, either.

Why bother when you can do it without the SELECT FOR UPDATE?

> BTW, one idea I was thinking about was that a SELECT FOR UPDATE NOWAIT
> behavior might simply not return the rows it couldn't acquire lock on,
> instead of erroring out. Not sure if this would be more or less useful
> than the error behavior, but I can definitely think of possible
> applications for it.
>
> > Also, I don't see this changing sematics like the regex flavor did.
>
> You're kidding. This is a much more fundamental change of behavior than

No, I am not.

> whether some seldom-used regex features work. In particular, we know
> that the regex behavior does not affect any other part of the system.
> I do not think any equivalent safety claims can be made for random
> hacking of whether LockAcquire succeeds or not.

It throws an error. I don't see how that could cause actual data
corruption or invalid data.

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