Re: Sharing more infrastructure between walsenders and regular backends (was Re: Switching timeline over streaming replication)

Simon Riggs <simon(at)2ndQuadrant(dot)com> writes:
> On 4 October 2012 17:23, Heikki Linnakangas <hlinnakangas(at)vmware(dot)com> wrote:
>> Perhaps we could make walsenders even more like regular backends than what I
>> was proposing, so that the replication commands are parsed and executed just
>> like regular utility commands. However, that'd require some transaction
>> support in walsender, for starters, which seems messy. It might become
>> sensible in the future if the replication command set gets even more
>> complicated, but it doesn't seem like a good idea at the moment.

> It's come up a few times now that people want to run a few queries
> either before or after running a base backup. ...
> Andres suggested to me the other day we make walsender more like
> regular backends. At the time I wasn't sure I agreed, but reading this
> it looks like a sensible way to go.

That was what I was thinking too, but on reflection there's at least one
huge problem: how could we run queries without being connected to a
specific database? Which walsender isn't.

regards, tom lane