Despite the performance hit, it is a stable hit. A hash lookup is done in O(1) time. An indexed database lookup can also be O(1). What I just said is a little misleading; Remember that big-O notation refers to order of growth based on growth of the dataset. But big-O notation doesn't deal with the fact that making one trip to the corner store takes less time than making one trip to the mall five miles away. So it's true that a hash lookup will be faster than a database lookup, but the important thing to remember is that order of growth is about the same. In the case of a hash lookup, there's essentially no growth in lookup time as the dataset grows. In the case of an indexed database, the same can be said, although the actual time will be longer for the database.

But where I'm going with all this is that if you are forced to the realization that memory constraints won't permit two hashes to be held in memory in tandem, it's time to start making tradeoffs. And one of the more common ways of lending scalability to a problem is turning to a database solution.


Dave

In reply to Re^5: two hashes occupying the same space by davido
in thread two hashes occupying the same space by jfroebe

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.