Re: count(*) vs count(columnX): Which one is better?

Hi,

>Regarding an SQL statement like this:
> SELECT count(*) FROM tableX where columnX='ABC'
>and
> SELECT count(columnX) FROM tableX where columnX='ABC'
>
>Which one is better for performance?

Oracle recognizes count(*) and is not evaluating every column in the count. But, if columnX has an index and has a not null constraint, the index will be used.

>Would there be some differences in performance and efficiency?

There sure is.

• Martin Jesterhoudt
• martinj(replace this by @)xs4all.nl

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