Beefy Boxes and Bandwidth Generously Provided by pair Networks
Think about Loose Coupling
 
PerlMonks  

Comment on

( #3333=superdoc: print w/replies, xml ) Need Help??
You're still racing between the select and the update, although something like this might work:

  • Update records where 'owner' column is null, with *my* value and timestamp now().
  • Select records with my owner value *or* where timestamp is older than threshold. This catches the case where some records have gone stale because a process died or what-have-you.
  • Process & delete selected records.
This way you're letting the database server handle updating the correct records. Depending on how speedily new records are added to the queue, it seems likely that processes will be working with records more than waiting for selects. Of course this approach doesn't help with splitting the records evenly between processes, but neither will a mutex.

In reply to Re^2: Database queue logic by moot
in thread Database queue logic by Marcello

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, 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
  • 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.
  • Log In?
    Username:
    Password:

    What's my password?
    Create A New User
    Chatterbox?
    and all is quiet...

    How do I use this? | Other CB clients
    Other Users?
    Others meditating upon the Monastery: (7)
    As of 2017-10-17 06:01 GMT
    Sections?
    Information?
    Find Nodes?
    Leftovers?
      Voting Booth?
      My fridge is mostly full of:

















      Results (218 votes). Check out past polls.

      Notices?