Tom Lane wrote: > Bruce Momjian <[EMAIL PROTECTED]> writes: > > Also, what does an in-memory bitmapped index look like? > > One idea that might work: a binary search tree in which each node > represents a single page of the table, and contains a bit array with > one bit for each possible item number on the page. You could not need > more than BLCKSZ/(sizeof(HeapTupleHeaderData)+sizeof(ItemIdData)) bits > in a node, or about 36 bytes at default BLCKSZ --- for most tables you > could probably prove it would be a great deal less. You only allocate > nodes for pages that have at least one interesting row.
Actually, I think I made a mistake. I was wondering what on-disk bitmapped indexes look like. -- 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
