At 02:54 AM 6/17/2001 +0200, Christian Gütter wrote:

>Hi,
>
>I am wondering how many records a table must contain so that
>indexing does not slow down selects.

The fundamental question of performance is how many pages
must be read off disk to support a query. Using an index
requires at a minimum four pages - the index root page, an
index page, a pointer page, and a data page. If the total
amount of data for a table is less than three pages worth,
then the non-indexed access is a certain winner - requiring
only a pointer page and the data pages.

Both styles require about equal amounts of data from the
pages table, so that can be ignored (I think. Mike may
correct me.)

The secondary question is which pages are in cache - and in
general, tables that require fewer than three data pages and
are referenced frequently, all pages are in cache.


Regards,

Ann
www.ibphoenix.com
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