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All the Perl that's Practical to Extract and Report

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  • But still not perfect. In the cases where it doesn't do what I want I've found temp tables to be invaluable in getting the query plan that I want. I have even pulled such tricks as creating temp tables, creating indexes on those temp tables, then doing my join.

    In any case the bigger underlying problem with MySQL is a fundamental design decision. The problem is that the time to compile a query is part of its run time. MySQL went the route of trying to make compilation fast. That means that it does a bad
  • The MySQL docs state pretty plainly that subqueries have not been optimized at all and won't be until the 6.0 release. In the meantime, you have to pay attention to how you use them. The stuff is a good resource.

    In most cases, it works out best to use derived tables (subqueries in the FROM clause), which are implemented with a temporary table and force the evaluation of the subquery before the JOIN order is determined. The only situation where this can be a negative is when you use LIMIT, since