You should investigate what kind query analysis tools your DBMS has.

In particular, check your RDBMS docs for "EXPLAIN PLAN". It's how you get the database to cough up the query execution plan, which will tell you things like where the database is having to do full table scans to satisfy your query. This'll give you suggestions about where indexes might help.

In reply to Re^3: Does DBI handle table alias? by dws
in thread Does DBI handle table alias? by punch_card_don

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