On Thu, Jan 27, 2005 at 21:17:56 -0800, Zavier Sheran <[EMAIL PROTECTED]> wrote: > quote from manual: > -- > Unfortunately, there is no similarly trivial query > that can be used to improve the performance of count() > when applied to the entire table > -- > > does count(1) also cause a sequential scan of the > entire table? It should be able to just use the > primary keys.
No it can't just use the index file, so that an index scan will be slower than the sequential scan unless there is a where clause restricting the number of rows to a small fraction (about 5%) of the table. Search the archives for if you want to read more about this. ---------------------------(end of broadcast)--------------------------- TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]
