>> True, but judging by the column name (only) I assumed triState was a
>> tri-state variable.

Ah, my fault. While the column does only have three or four possible
states, the index is useful for us. All we need is to look at the
performance results with or without the index. Now, that's not to say
that this is a good design. We would probably be better off putting
those few records that benefit from the record in another table, but
that's another story.



-----Original Message-----
From: Helen Borrie [mailto:helebor@...]
Sent: Monday, August 04, 2003 9:05 PM
To: firebird-support@yahoogroups.com
Subject: RE: [firebird-support] Table Scans and !=


At 05:20 PM 4/08/2003 -0700, you wrote:

>Well, in a black box world, I can't really do "< 2", but I can
>substitute "!=" with an "IN" of everything but the value I was going to
>compare "!=" to.

True, but judging by the column name (only) I assumed triState was a
tri-state variable.

>Why shouldn't I have triState indexed? In IBExpert the query seems to

be

>using the index if I use "IN (0,2)" but not if I use "!=1".

If your triState column is in fact a tri-state variable, then the
selectivity is impossibly low. This is a real killer if there's a
chance
that the optimizer would use that index.

Where have you been? If I had 1 dollar for every time I (never mind
anyone
else) have explained this, I wouldn't need to work again for the rest of
my
life.

heLen



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