Re: Postgres refusing to use >1 core

> This is a problem I encounter constantly wherever I go. Programmer
> selects millions of rows from giant table. Programmer loops through
> results one by one doing some magic on them. Programmer submits queries
> back to the database. Even in batches, that's going to take ages.

Reminds me of a recent question on stackoverflow :

http://stackoverflow.com/questions/5952020/how-to-optimize-painfully-slow-mysql-query-that-finds-correlations

And the answer :


http://stackoverflow.com/questions/5952020/how-to-optimize-painfully-slow-mysql-query-that-finds-correlations/5954041#5954041

OP was thinking "row-based", with subqueries in the role of "doing some
magicm".
Using a set-based solution with cascading WITH CTEs (and using the
previous CTE as a source in the next one for aggregation) => 100x speedup !