Re: Suspicious behaviour on applying XLOG_HEAP2_VISIBLE.

On 15 April 2016 at 20:01, Andres Freund <andres(at)anarazel(dot)de> wrote:

> On 2016-04-15 19:59:06 +0100, Simon Riggs wrote:
> > For me, the issue is that we need to do something to catch bugs. The
> > existing code does not have any test at all to check whether we are doing
> > the wrong thing - it just lets the wrong thing happen.
>
> But sending the message, without assigning an xid, *IS* the right thing
> to do here? We shouldn't assign an xid, and we need to send the message
> out to the standbys.
>
>
> > Fixing it by forcing a new behaviour might be the right thing to do going
> > forwards, but I don't much like the idea of forcing new behaviour in back
> > branches. It might fix this bug, but can easily cause others.
>
> What's your alternative? Assigning an xid in the middle of vacuum isn't
> ok, breaking vacuum isn't either?
>

In my understanding we have two choices for this bug

1) assign an xid so it forces sending a message (message plus xid)
2) send a message without assigning an xid (message only)

(1) seems like it is worse for backpatching, IMHO, though I am willing to
hear other thoughts or options

--
Simon Riggs http://www.2ndQuadrant.com/
<http://www.2ndquadrant.com/>
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