Simon Riggs <simon@2ndquadrant.com> writes:
> From here, another proposal. We have a GUC called count_uses_estimate
> that is set to off by default. If set to true, then a count(*) will use
> the planner logic to estimate number of rows in the table and return
> that as the answer, rather than actually count the row.

Ugh. Why not just provide a function to retrieve the planner estimate,
but *not* call it count(*)? It would fit nicely with the contrib/dbsize
stuff (or I should say, the stuff formerly in dbsize...)

regards, tom lane

---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match