Beefy Boxes and Bandwidth Generously Provided by pair Networks
There's more than one way to do things
 
PerlMonks  

Comment on

( #3333=superdoc: print w/ replies, xml ) Need Help??

Agree with BrowserUK ... 500 million integers is a lot to index, and if you aren’t searching for anything, it’s pure overhead to get “sorted answers” that way.   But a good external sorting package would have no particular difficulty.

Ideally, you would arrange the whole data-processing flow which includes this file so that everything gets put into a known sort-sequence early and things are done in such a way as to keep it that way from one step to the next.   So you might have a 500 million record master-file which is simply “known to be” sorted, and you manipulate that file in ways that require it to be that way and which keep it that way.   This avoids searching, and it avoids repetitive sorting.   It also avoids indexes and the overhead of the same.   At the same time, though, you do not want to schleb a bunch of data through disk-reads and disk-writes if you are not actually doing anything with most of it.

Obviously, RAM is the fastest resource and it avoids I/O entirely ... provided that virtual-memory swapping is not going on, which can be killer.   Your strategy entirely depends on your situation, and sometimes you can get a lot of mileage simply by chopping a large file into smaller chunks so that each one does fit in the RAM that you have without swapping.

The key here is ... “without swapping.”   If you are doing high volume processing “in memory” to avoid I/O, but push the limit so that you start to swap, not only is “I/O going on,” but it can be of a particularly murderous kind.


In reply to Re^2: "Out of memory" problem by sundialsvc4
in thread "Out of memory" problem by abdullah.yildiz

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!
  • 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, 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, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • Outside of code tags, you may need to use entities for some characters:
            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.
  • Log In?
    Username:
    Password:

    What's my password?
    Create A New User
    Chatterbox?
    and the web crawler heard nothing...

    How do I use this? | Other CB clients
    Other Users?
    Others rifling through the Monastery: (7)
    As of 2014-09-20 09:05 GMT
    Sections?
    Information?
    Find Nodes?
    Leftovers?
      Voting Booth?

      How do you remember the number of days in each month?











      Results (157 votes), past polls