Ron Mayer <[EMAIL PROTECTED]> writes: > I did quite a bit more playing with this, and no matter what the > correlation was (1, -0.001), it never seemed to have any effect > at all on the execution plan.
> Should it? With a high correlation the index scan is a much better choice. I'm confused. Your examples show the planner correctly estimating the indexscan as much cheaper than the seqscan. > logs2=# explain analyze select count(*) from fact_by_dat where dat='2002-03-01'; > NOTICE: QUERY PLAN: > Aggregate (cost=380347.31..380347.31 rows=1 width=0) (actual >time=77785.14..77785.14 rows=1 loops=1) > -> Seq Scan on fact (cost=0.00..379816.25 rows=212423 width=0) (actual >time=20486.16..77420.05 rows=180295 loops=1) > Total runtime: 77785.28 msec Cut-and-paste mistake here somewhere, perhaps? The plan refers to fact not fact_by_dat. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]