Re: pg_dump issues

Alvaro Herrera <alvherre@commandprompt.com> writes:
> Excerpts from Tom Lane's message of lun oct 03 01:47:18 -0300 2011:
>> (Without cassert, it looks like LockReassignCurrentOwner is the next
>> biggest time sink; I'm wondering if there's some sort of O(N^2) behavior
>> in there.)

> That seems fishy.  Even if there weren't quadratic behavior, should this
> be called at all?  AFAIK it should only be used on cases where there are
> subtransactions at work, and I don't think pg_dump uses them.

I wondered that too, but the calls are legit --- they're coming from
PortalDrop.

It appears that most of the calls don't actually have anything to do,
but they're iterating through a rather large local lock table to find
that out.  We probably ought to think of a way to avoid that.  The trick
is to not make performance worse for typical small transactions that
aren't holding many locks (which I think was the design center for this
to begin with).
        regards, tom lane