Is this a rewording of your question - how do a read from a compressed file without having to uncompress it completely first, then read through the temporary uncompressed file?

If that is what you are asking then try this (assuming the compressed file contains text)

    use IO::Uncompress::Gunzip qw( $GunzipError );

    my $file = "somefile";
    my $gz = new IO::Uncompress::Gunzip $file
          or die "Cannot open $file: $GunzipError\n" ;

    while (<$gz>)
    {
        # whatever...
    }
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