Re: Listen / Notify rewrite - Mailing list pgsql-hackers

From Andrew Chernow
Subject Re: Listen / Notify rewrite
Date
Msg-id 4AFDA316.1050207@esilo.com
Whole thread Raw
In response to Re: Listen / Notify rewrite  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
Tom Lane wrote:
> "Greg Sabino Mullane" <greg@turnstep.com> writes:
>> Talk of efficiency also seems silly here - using
>> shared memory is already way more efficient than our current listen/notify
>> system.
> 
> Except that the proposed implementation spills to disk.  Particularly if
> it has to have support for large payloads, it could very well end up
> being a lot SLOWER than what we have now.
> 

True, but do you really consider it to be a common case that the notify 
system gets soo bogged down that it starts to crawl?  The problem would 
be the collective size of notify structures + payloads and whether that 
would fit in memory or not.  This leads me to believe that the only 
safety in smaller payloads is *possibly* a smaller chance of bogging it 
down, but that all depends on the usage pattern of smaller vs. larger 
payloads which is system specific.

-- 
Andrew Chernow
eSilo, LLC
every bit counts
http://www.esilo.com/


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