I also had good results with HTTPD::Log::Filter extracting the query strings from my access_log.

my $hlf = HTTPD::Log::Filter->new(capture => [ qw(request status) ]);
...
    next unless $hlf->filter($ac_line);
    next unless $hlf->status == 200;
    my ($method, $query, $http_version) = split(' ', $hlf->request);
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