Christo Du Preez <christo@mecola.com> writes:
> Fast:
> "public";"layertype";"parentid";0.98797;4;2;"{4,1}";"{0.00902256,0.00300752}";"";-0.142857
> Slow:
> "public";"layertype";"parentid";0.00745157;4;7;"{300}";"{0.976155}";"{1,1,4,5,8,12}";0.92262
Well, those statistics are almost completely different, and what the
slow one says is that parentid = 300 accounts for 97% of the table.
So that's why you get different plans. If that is not reflective of
reality, then you have not ANALYZEd the table lately.
Maybe it's a pilot-error problem, like not doing the ANALYZE as a user
with sufficient privileges? IIRC you have to be table owner, database
owner, or superuser to ANALYZE.
regards, tom lane