ups, the question is simply what is low-selectivity? The distribution of
values?

On Mon, 2002-04-22 at 16:34, Jan Agermose wrote:

just to be sure. What is meant by low-selectivity and does it change
(logtype, id) to (id, logtype). id being the primary key

Jan

On Mon, 2002-04-22 at 16:05, Helen Borrie wrote:

At 03:24 PM 22-04-02 +0200, Svein wrote:
> >does multicolumn indexes make sense if you use them in a non multicolumn
> >query?
>
>Yes, because duplicates in an index make things slow down. When running the
>query, IB will only use those parts of the index that are useful.

Actually, you must define this index with the low-selectivity column first,
followed by the unique id in second spot.

cheers,
H.


All for Open and Open for All
Firebird Open SQL Database · http://firebirdsql.org ·
http://users.tpg.com.au/helebor/
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