Hi,

1) doesn't matter. But if you want a sorting or even select the first x records above 0 you should use ascending

2) a key will help but there shouldn't be any measurable difference if ascending or descending

Karsten

On 18.02.2011 14:40, Sergio H. Gonzalez wrote:
>
> Hello... simple questions (I think!):
>
> 1) having a numeric field, if I want to select all the values > 0, is
> better to have an descending index on that field? or just a ascending one?
>
> 2) having a date field, if I want to select all the records with null.
> It helps to have an index on that field? If so, would it be ascending or
> descending?
>
> I know, FB uses the index for selecting nulls of a date field (the plan
> analizer shows me that) but I wander if it really helps.
>
> thanks!
>
> -s
>
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>
>


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