> Mmmm, quite a difference.. Looks like Anns original suggestion is better
> (less selective first).

Indeed :)

So Ann, putting the less-selective first is better for avg data length
and doesn't matter for the index effectiveness, right?

Learned another thing today :)


With regards,

Martijn Tonies
InterBase Workbench - the developer tool for InterBase
http://www.upscene.com

Firebird Workbench - the developer tool for Firebird
http://www.upscene.com

Upscene Productions
http://www.upscene.com

"This is an object-oriented system.
If we change anything, the users object."

>
>
>
> At 03:19 PM 9/30/2002 -0400, Ann W. Harrison wrote:
>
> >OK, time for some actual tests. Theoretically that guy is all wet.
>
>
> The first index puts the less selective column (varchar 50 with
> two distinct values) first. The second puts it last. Notice
> the average data lengths....
>
> Index B1 (0)
> Depth: 3, leaf buckets: 510, nodes: 265954
> Average data length: 1.00, total dup: 0, max dup: 0
> Fill distribution:
> 0 - 19% = 0
> 20 - 39% = 1
> 40 - 59% = 0
> 60 - 79% = 0
> 80 - 99% = 509
>
> Index B2 (1)
> Depth: 4, leaf buckets: 4502, nodes: 265954
> Average data length: 60.00, total dup: 0, max dup: 0
> Fill distribution:
> 0 - 19% = 0
> 20 - 39% = 1
> 40 - 59% = 0
> 60 - 79% = 0
> 80 - 99% = 4501
>
>
>
>
>
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