Index the file in one pass; then use the index to seek the id/data directly:

#! perl -slw
use strict;

my %idx; ## Index the file
$idx{ <> } = tell( ARGV ), scalar <> until eof();

for ( 1 .. 1000 ) {
    my $id = getNextId( ... );
    seek ARGV, $idx{ $id };
    scalar <>; # discard id line (or verify)
    print scalar <>; ## access data;
}

[download]

Untested code for flavour only.

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In reply to Re: Reading HUGE file multiple times by BrowserUk
in thread Reading HUGE file multiple times by Anonymous Monk

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