What are you optimizing than? Execution speedup cq load time?
Are you sure that it takes significantly more time to do an
additional query to the server? I guess the connection is not
closed between the statement. Maybe the DB is on the same box
as the webserver.
And even if it takes some additional timeframe (probably very
small, test it!) for the query, is it worth the worse
maintainability of perl code vs the SQL code?
I generally would answer 'no', but your situation may be
different. As ppl say: only optimize the code that needs
optimization. Optimization leads to less quality code,
so be sure you need it. Just consider what you are doing.