Re: WAL Info messages - Mailing list pgsql-hackers

From Tom Lane
Subject Re: WAL Info messages
Date
Msg-id 28858.1260802314@sss.pgh.pa.us
Whole thread Raw
In response to Re: WAL Info messages  (Greg Stark <gsstark@mit.edu>)
Responses Re: WAL Info messages  (Simon Riggs <simon@2ndQuadrant.com>)
Re: WAL Info messages  (Simon Riggs <simon@2ndQuadrant.com>)
List pgsql-hackers
Greg Stark <gsstark@mit.edu> writes:
> What happens on the slave when normal NOTIFYs are generated on the
> master? IIRC NOTIFYs are wal-logged so I imagine LISTEN on the slave
> would just work and a plain old NOTIFY/LISTEN would suffice for this
> use case?

Nothing happens: NOTIFYs are *not* WAL-logged, and it would be quite
against the intended use-case to have them be.

If you're hoping that processes on the slave could LISTEN for events
happening on the master, we'd have a bit of a conflict.  This might be
an example of a case where we need that "are we doing HS" flag that
Simon insists we don't need.
        regards, tom lane


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