Re: relcache refcount

Alvaro Herrera <alvherre@dcc.uchile.cl> writes:
> Ok, I created a function to copy a hash table (from dynahash).  So now
> at subtransaction start the RelationIdCache and RelationSysNameCache
> hash tables are copied, and if the subtransaction aborts the previous
> hash tables are restored.

I don't think that will do; what about updates absorbed during the
subtrans from other backends' changes?  In any case, copying the whole
cache state during every subtrans start is not the kind of overhead
I wish to pay ...

> Regarding the lock mechanism, I simply added some code to LockReleaseAll
> so it gets the array of committed child Xids; on subtransaction abort,
> the whole lock struct is scanned just like it's done on main transaction
> abort; only those locks affiliated with one of the given Xids are
> released.  This is naive, so if it's incorrect please comment.

Not sure; it's been a long day and I'm tired ... will think about it
tomorrow ...

> PS: Either the list server is getting very slow or it has started to
> lose mail.  I asked yesterday whether it was OK to copy the hash but
> apparently the mail didn't make it to the list.  Is there something
> happening?

I haven't seen that one.  Check your subscription settings to see
whether you'd be notified if the list bot delayed your post for some
reason.
        regards, tom lane