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Re^2: Database queue logic

by moot (Chaplain)
on Jun 14, 2005 at 14:34 UTC ( #466577=note: print w/replies, xml ) Need Help??

in reply to Re: Database queue logic
in thread Database queue logic

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.

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Re^3: Database queue logic
by Marcello (Hermit) on Jun 15, 2005 at 08:05 UTC
    Good solution,

    I will try this approach shortly.

    Thanks all!

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