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.


---------------------------(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

Reply via email to