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    <p>I don't think any of the DBM packages have an API for retrieving a random key, or for retrieving keys by index number. You can look up a particular key, or you can read through all the keys in whatever order the database chooses to return them in (which may change if the database is modified, and may or may not be "random" enough for whatever you want to do).</p> <p>You could read through all the keys and pick one, but that would require reading the entire database each time (or at least a sizable chunk of it), and that's probably too slow.</p> <p>I think you'll need to rearrange your data structure.</p> <ol> <li><p>You could use a real SQL database (like <a href="http://search.cpan.org/perldoc?DBD::SQLite" rel="nofollow noreferrer">SQLite</a>), so you could look up rows both by a sequential row number and by URL. This would be the most flexible.</p></li> <li><p>You could use a sequential integer as the key for your DBM file. That would make picking a random one easy, but you could no longer look up entries by URL.</p></li> <li><p>You could use two DBM files: the one you have now and a second keyed by sequential integer with the URL as value. (Actually, since URLs don't look like integers, you could store both sets of records in the same DBM file, but that would complicate any code that uses <code>each</code>.) This would use twice the disk space, and would make inserting/removing entries a bit more complicated. You'd probably be better off with approach #1, unless you can't install SQLite for some reason.</p></li> </ol>
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    1. POHow do I access random element in a Perl DBM hash?
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    1. COrelated question for 'real SQL databases': http://stackoverflow.com/questions/19412/how-to-request-a-random-row-in-sql
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