Re: why does count take so long?

How about keeping counts of inserts, deletes and updates per table per
transaction as part of the live statistics?



Tom Lane wrote:
> 
> I said:
> > Greg Stark <gsstark@mit.edu> writes:
> >> Things like count(*) could use int4 until it overflows though.
> 
> > I don't see a reasonable way for an aggregate to change state datatype
> > on the fly; otherwise this would be a great solution.
> 
> On the other hand, the cost is imposed by the generic aggregate
> definition that says the aggregate state transition function is an
> ordinary function.  This is fine for user-defined aggregates, but there
> is no law that says that all the built-in aggregates must use that same
> API.  We could probably invent some API that allows COUNT(*) to keep its
> running count someplace where it needn't be re-palloc'd on every cycle.
> Something to think about for 7.5 (too late for 7.4 I fear).
> 
>                         regards, tom lane
> 
> ---------------------------(end of broadcast)---------------------------
> TIP 2: you can get off all lists at once with the unregister command
>     (send "unregister YourEmailAddressHere" to majordomo@postgresql.org)