| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
| Cc: | Joachim Wieland <joe(at)mcknight(dot)de>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Listen / Notify rewrite |
| Date: | 2009-11-15 21:48:11 |
| Message-ID: | 24189.1258321691@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Simon Riggs <simon(at)2ndQuadrant(dot)com> writes:
> On Wed, 2009-11-11 at 22:25 +0100, Joachim Wieland wrote:
>> 3. Every distinct notification is delivered.
>> Regarding performance, the slru-queue is not fsync-ed to disk
> These two statements seem to be in opposition. How do you know a
> notification will be delivered if the queue is non-recoverable?
You misunderstand the requirements. LISTEN notifications are *not*
meant to survive a database crash, and never have been. However,
so long as both client and server stay up, they must be reliable.
If the client has to poll database state because it might have
missed a notification, the feature is just a waste of time.
regards, tom lane
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