Which is more efficient: two regexp's or one regexp with alternation?

[Kelly Jones <ke...@gmail.com>]

If I want to block subjects matching "foo" or "bar", is it more
efficient to write two regexps or a single "foo|bar" regexp?

I'd think a single regexp is more efficient, but SpamAssassin ships w/
rule-sets that have multiple rules. Given how many spams people get,
even a small improvement in efficiency would help?

Or are there multiple rules because the scores are different and have
to be optimized differently?

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Re: Which is more efficient: two regexp's or one regexp with alternation?

[Theo Van Dinter <fe...@apache.org>]

On Tue, Jan 16, 2007 at 06:23:48PM -0700, Kelly Jones wrote:
> If I want to block subjects matching "foo" or "bar", is it more
> efficient to write two regexps or a single "foo|bar" regexp?

It'll be more efficient to do a single regexp.

> Or are there multiple rules because the scores are different and have
> to be optimized differently?

Yes.  Rules have different hit rates, so they need to get different
scores because it's better for overall efficacy.

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