Tom Lane wrote: > Bruce Momjian <[EMAIL PROTECTED]> writes: > > Updated TODO: > > > * Allow the creation of bitmap indexes which can be quickly combined > > with other bitmap indexes > > This TODO item description is fundamentally misleading. > > The point was *not* about making "bitmap indexes", which on its face > suggests a persistent on-disk data structure comparable to our existing > index types. The point was about using transient in-memory bitmaps as > an interface between the on-disk indexes and accessing the table proper.
There are two separate issues --- on-disk bitmap indexes and on-the-fly in-memory created ones. I tried to mention both but obviously it wasn't clear. Here is new wording: * Allow non-bitmap indexes to be combined by creating bitmaps in memory Bitmap indexes index single columns that can be combined with other bitmap indexes to dynamically create a composite index to match a specific query. Each index is a bitmap, and the bitmaps are bitwise AND'ed or OR'ed to be combined. They can index by tid or can be lossy requiring a scan of the heap page to find matching rows. * Allow the creation of on-disk bitmap indexes which can be quickly combined with other bitmap indexes -- 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 2: you can get off all lists at once with the unregister command (send "unregister YourEmailAddressHere" to [EMAIL PROTECTED])
