Re: Failed to request an autovacuum work-item in silence

Masahiko Sawada wrote:

> While reading the code, I realized that the requesting an autovacuum
> work-item could fail in silence if work-item array is full. So the
> users cannot realize that work-item is never performed.
> AutoVacuumRequestWork() seems to behave so from the initial
> implementation but is there any reason of such behavior? It seems to
> me that it can be a problem even now that there is only one kind of
> work-item. Attached patch for fixing it.

Hmm, yeah.

I think it would be better to return false to caller, and have them
report the failure.  Then they're in a better position to place an
accurate log message -- for instance indicating the relation name rather
than just OID, and specify work item type rather than some weird
integer.  (I think the ereport() should definitely be *outside* the
locked section, in any case.)

I'm inclined to change the API of AutoVacuumRequestWork even in branch
10.  Since this stuff is not nicely extensible (c.f. perform_work_item),
it doesn't seem likely that any outside code is calling it yet.  Once we
have hooks to register worker functions and stuff, it'll become more of
a problem.

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
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