Re: SELECT FOR UPDATE NOWAIT

Paulo Scardine wrote:
> LockAcquire has a "dontWait" parameter, which do just what I want.
> 
> The executor level calls "heap_open(relid, RowShareLock)" when doing "FOR
> UPDATE"s.
> Should we define something like RowShareLockNoWait, so heap_open() or other
> lower level functions can call LockAcquire() with dontWait set?
> 
> By the way, is this kind of question on-topic for pgsql-hackers?

I think there are two issues with implementing nowait locking:

If we have special syntax for FOR UPDATE, we will need it for other
commands that need no wait behavior, and after a while they all carry
around that cruft --- SET seems easier and more useful.

Second, I don't think we want to carry around a NOWAIT boolean in all
our structures --- a SET would control it easier.  The SET can be
checked right in the lock code, and I think having it control only
exclusive locks would do almost everything we want.

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