|Subject||RE: [firebird-support] Table Scans and !=|
>> True, but judging by the column name (only) I assumed triState was aAh, my fault. While the column does only have three or four possible
>> tri-state variable.
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.
From: Helen Borrie [mailto:helebor@...]
Sent: Monday, August 04, 2003 9:05 PM
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 canTrue, but judging by the column name (only) I assumed triState was a
>substitute "!=" with an "IN" of everything but the value I was going to
>compare "!=" to.
>Why shouldn't I have triState indexed? In IBExpert the query seems tobe
>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
that the optimizer would use that index.
Where have you been? If I had 1 dollar for every time I (never mind
else) have explained this, I wouldn't need to work again for the rest of
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