On Mon, 15 Oct 2001, Szabo Zoltan wrote: > Hi, > > I have that: > > 1) > db=> explain select pxygy_pid from prog_dgy_xy where pxygy_pid=12121; > NOTICE: QUERY PLAN: > > Group (cost=0.00..29970.34 rows=921 width=4) > -> Index Scan using progdgyxy_idx2 on prog_dgy_xy > (cost=0.00..29947.32 rows=9210 width=4) > > than: > 2) > db=> explain select pxygy_pid from prog_dgy_xy where pxygy_pid>12121; > NOTICE: QUERY PLAN: > > Group (cost=66927.88..67695.39 rows=30700 width=4) > -> Sort (cost=66927.88..66927.88 rows=307004 width=4) > -> Seq Scan on prog_dgy_xy (cost=0.00..32447.66 rows=307004 > width=4) > > I making some banchmarks on: oracle vs postgres vs mysql. And this is > breaking me now;) Mysql and oracle width same table and index use that > index on pxygy_pid; > I had vacuum before.
I assume you mean you did a vacuum analyze (a plain vacuum isn't sufficient). If you did just do a regular vacuum, do a vacuum analyze to get the updated statistics. How many rows actually match pxygy_pid>12121? Is 307000 rows a reasonable estimate? How many rows are in the table? ---------------------------(end of broadcast)--------------------------- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/users-lounge/docs/faq.html
