> I have a table where I need the maximum value from.

Ann and Lucas have both given you the answer to your problem, I am
just a little concerned about what you may be trying to do.

Why do you want the maximum? If you were intending on adding 1 to
generate the next key, then you are in for a bumpy ride, if this is
not the key field (which I hope based on that it looks like a
timestamp), then that is fine and your approach is good (if it had the
descending index).

Adam




I ran "select

> max(LastUpdated) from TableName" SQL against it and got the following
> stats:
>
> Plan
> PLAN (TAXYEAR NATURAL)
>
> Adapted Plan
> PLAN (TAXYEAR NATURAL)
>
> ------ Performance info ------
> Prepare time = 0ms
> Execute time = 15ms
> Avg fetch time = 15.00 ms
> Current memory = 742,144
> Max memory = 877,436
> Memory buffers = 2,048
> Reads from disk to cache = 0
> Writes from cache to disk = 6
> Fetches from cache = 392
>
> Then I created an index on LastUpdated:
>
> Create Index TableNameIdx1 on TableName(LastModified);
>
> and when I rerand the select max()... against it, it is still using
> the natural plan:
>
> Plan
> PLAN (TAXYEAR NATURAL)
>
> Adapted Plan
> PLAN (TAXYEAR NATURAL) // Why natural if an index exists?
>
> ------ Performance info ------
> Prepare time = 0ms
> Execute time = 0ms
> Avg fetch time = 0.00 ms
> Current memory = 812,408
> Max memory = 947,700
> Memory buffers = 2,048
> Reads from disk to cache = 0
> Writes from cache to disk = 6
> Fetches from cache = 392
>
> Both use the natural plan, bot have the same number of fetches from
> the cache. Shouldn't it use the index in the second case? Am I
> misunderstanding what is happening?
>
> Thanks
> Ed Dressel
>