I was pair programming with the great magician Keith yesterday when he pointed out something interesting when checking if objects or relations exist in a collection.

To check if there were any items present in a collection I would do something like this:

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object.relation.present?

Keith told me to use:

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object.relation.any?

Turns out that the any? method will perform a COUNT (*) SQL query where as the present? method will perform a SELECT (*) which is infinitely slower than performing a count.

So from now on i’ll be using the any? method instead of present?