Here's another thought - if your database will only ever be used to find intersections, why not pre-calculate all of them in some manner? Just because your database is normalized doesn't mean it's the right schema for your purpose.

For example, I have selectively denormalized my reporting database, just to reduce the number of table joins. Since I control all writing to the database and the database is specialized to a given purpose, this is a good breaking of the rules.

Being right, does not endow the right to be rude; politeness costs nothing.
Being unknowing, is not the same as being stupid.
Expressing a contrary opinion, whether to the individual or the group, is more often a sign of deeper thought than of cantankerous belligerence.
Do not mistake your goals as the only goals; your opinion as the only opinion; your confidence as correctness. Saying you know better is not the same as explaining you know better.

In reply to Re^2: Basic Perl array intersection faster than mysql query join. by dragonchild
in thread Basic Perl array intersection faster than mysql query join. by punch_card_don

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