5. ã»ããã¢ãã $ git clone https://github.com/south37/sql-tuning $ git checkout sql-tuning $ bin/rake db:create $ pg_restore -j 4 --verbose --no-acl --no-owner -d sql-tuning-dev db.dump 7. ActiveRecord::Relation#explain $ Job.joins(:company).group('companies.country').where('companies.id < 1000â) .select('companies.country', 'COUNT(jobs.id)').explain => EXPLAIN for: SELECT companies.country, COUNT(jobs
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