What "fast" means in this situation will have a lot to do with how much physical memory you have. At 10+ million entries, how close to virtual memory thrashing are you? If you're close, then keys %HASH might push you over the edge.

I'd be inclined to try an approach that doesn't add to the memory overhead. Something like 

    my @largest;
    while ( my($k,$v) = each %HASH ) {
        if ( @largest < $N ) {
            push @largest, $v;
        } else {
            # if $v is greater than the smallest element
            # in @largest, replace that element with $v
        }
    }

[download]
I've left you with a little work to do, but that's the general idea.

In reply to Re: *Fastest* way to print a hash sorted by value by dws
in thread *Fastest* way to print a hash sorted by value by smellysocks

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.