Both Corion and Techcode are true, but you can choose something between...

If you cannot, for some reasons, filter the data by SQL, you can use repeatedly $sth->fetchall_arrayref($slice, $max_rows) It allows to fetch, for instance, maximally 10000 rows at the same time and to not exhaust memory on the client side, when unpredicted amount of rows has to be returned.

In reply to Re^3: latency and round-trips by pajout
in thread DBI Queries take half an hour by joec_

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