Hannu Krosing wrote: > Eric Ridge kirjutas R, 09.01.2004 kell 01:16: > > > Forgetting about composite indexes for a moment, is postgres even > > capable of doing 2 index scans in this situation? Does it know how do > > take the intersection of two scans? > > Not currently, but it has been in TODO for quite some time: > > * Use bitmaps to fetch heap pages in sequential order [performance] > * Use bitmaps to combine existing indexes [performance]
And this the foundation of bitmapped indexes, as I understand it, and is used for "star" joins, popular with data warehousing. Rather than use those terms, I spelled out the actual behavior we want. -- Bruce Momjian | http://candle.pha.pa.us [EMAIL PROTECTED] | (610) 359-1001 + If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square, Pennsylvania 19073 ---------------------------(end of broadcast)--------------------------- TIP 9: the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
