> -----Original Message----- > From: pgsql-performance-owner@xxxxxxxxxxxxxx [mailto:pgsql-performance- > owner@xxxxxxxxxxxxxx] On Behalf Of Steinar H. Gunderson > A merge join requires sorted inputs. > > > Most of the time was spent sorting the parameters parameters table by > > opset_num even though opset_num is indexed. Isn't Postgres able to walk > the > > index instead of sorting? > > The time of an index scan vs. a sequential scan + sort depends on several > factors, so it's not just a matter of walking the index whenever there is > one. I was just looking this over again and I realized I misread the query plan. The slowest step was the Bitmap Heap Scan not the sort. (The sort was relatively fast.)
