Matching 50,000 anything against a database is going to be a pain. I would do one select though, draw the whole table into a hash of ids, then compare your array to it. This trades off memory for disk and CPU time; for this much data it is probably worth it, but not a good idea when the table contains millions of records.

Any faster scheme would depend on properties of the table; for instance, if the user ids are integers and have longish sequences of values with no gaps, then you could store the start and end of sequences and so on.

In reply to Re: Comparing an array to a DBI table by TheoPetersen
in thread Comparing an array to a DBI table by oakbox

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