Paul Tuckfield <[EMAIL PROTECTED]> writes: > In the case of select count(*), one optimization is to do a scan of the > primary key, not the table itself, if the table has a primary key. In a > certain commercial, lesser database, this is called an "index fast full > scan". It would be important to scan the index in physical order > (sequential physical IO) and not in key order (random physical IO)
That won't work because you still have to hit the actual tuple to determine visibility. -Doug ---------------------------(end of broadcast)--------------------------- TIP 3: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly