"David M. Richter" <David.M.Richter@freenet.de> writes:
> The query with the 3 tables is faster than the query with 2 tables.
How you figure that?
> time psql -d compare -c "SELECT patient.*,study.* FROM
> patient,study,relpatient_study000 r0 WHERE
> (patient.chiliOID=r0.parentOID AND study.chiliOID=r0.childOID) order by
> patient.name using <" > 3tableni
> 1.671u 0.130s 0:11.14 16.4% 0+0k 0+0io 208pf+0w
> time psql -d pacs -c "SELECT patient.*,study.* FROM patient,study WHERE
> (patient.chiliOID=study.patientOID ) order by patient.name using <" >
> 2tableni
> 1.730u 0.120s 0:09.44 19.5% 0+0k 0+0io 208pf+0w
9.44 vs 11.14 seconds looks like a clear advantage for the second query
to me...
regards, tom lane