On Fri, 2006-02-10 at 16:06, Tim Jones wrote: > > I am trying to join two tables and keep getting a sequential scan in > the plan even though there is an index on the columns I am joining > on. Basically this the deal ... I have two tables with docid in them > which is what I am using for the join. > SNIP > select * from documentversions join clinicaldocuments on > documentversions.documentidentifier > = clinicaldocuments.dssdocumentidentifier where > documentversions.documentstatus = 'AC'; > > does index scan > but if I change the order e.g > > select * from clinicaldocuments join documentversions on > clinicaldocuments.dssdocumentidentifier > = documentversions .documentidentifier where > clinicaldocuments.patientidentifier= 123; OK. I'm gonna make a couple of guesses here: 1: clinicaldocuments.patientidentifier is an int8 and you're running 7.4 or before. 2: There are more rows with clinicaldocuments.patientidentifier= 123 than with documentversions.documentstatus = 'AC'. 3: documentversions.documentidentifier and clinicaldocuments.dssdocumentidentifier are not the same type. Any of those things true?
