Optimistic locking is useful for interfaces where you have a person interactively updating a record. You check out a copy of the record, give the user all the time in the world to work out what changes they want to make, then, when the user goes to apply the changes, if the record was changed after you checked out a copy, then you deny the update and force the user to start over. Those last steps need to be done atomicly which is usually where locks come into play. But just ensuring that update operations for any given record get processed one-at-a-time from a single queue will also make updates atomic.

To handle delete requests with this, you'd need to keep a place-holder for deleted records that consisted only of the revision number. I'd just let the external code decide what it wants to use as a place-holder for deleted records and use the update operation instead of the delete operation.

- tye        

In reply to Re^11: Randomization as a cache clearing mechanism (optimistic locking) by tye
in thread Randomization as a cache clearing mechanism by demerphq

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.