Csaba Nagy wrote:
I only know to answer your no. 2:
2) What about the issue with excessive locking for foreign keys when
inside a transaction? Has that issue disappeared in 8.2? And if not,
would it affect similarly in the case of multiple-row inserts?
The exclusive lock is gone already starting with 8.0 IIRC, a
non-exclusive lock on the parent row is used instead. Thing is that this
is still too strong ;-)
The proper lock would be one which only prevents modification of the
parent key, other updates would be safe on the same row.
In any case, the current behavior is much better than what was before.
*Much* better, I would say --- though you're still correct in that it is
still
not the right thing to do.
In particular, with the previous approach. there was a serious performance
hit when concurrent transactions reference the same keys --- that is, after
having taken measures to avoid deadlocks, some transactions would have
to *wait* (for no good reason) until the other transaction is completed and
the exclusive-access lock is released. For high-traffic databases this
can be
a quite severe performance hit. I'm glad it has been fixed, even if only
partially.
Thanks,
Carlos
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