Re: composite index

Laly wrote:
> Hello,
>
>
> Suppose we have a huge table T(a, b, ...)
> There is a primary key on (a, b).
> Can we gain some time on queries like
> select *
> from T
> where a = ...
> by creating a new nonunique index on column a.
>
>
> Thanks in advance,
>
>
> Laly.

Version number?

Possibly. It is worth testing in a specific situation.

Certainly one on 'b' would be more likely to generate an improvement provided the cost of the indexes maintenance isn't larger than the improvement.

There is no general rule other than try it and find out.

-- 
Daniel Morgan
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