Re: truncating pg_multixact/members

Tom Lane escribió:
> Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> writes:
> > In this new version, I added a couple of fields to VacuumStmt node. How
> > strongly do we feel this would cause an ABI break? Would we be more
> > comfortable if I put them at the end of the struct for 9.3 instead?
>
> In the past we've usually added such members at the end of the struct
> in back branches (but put them in the logical place in HEAD). I'd
> recommend doing that just on principle.

Okay.

> > Also, AutoVacOpts (used as part of reloptions) gained three extra
> > fields. Since this is in the middle of StdRdOptions, it'd be somewhat
> > more involve to put these at the end of that struct. This might be a
> > problem if somebody has a module calling RelationIsSecurityView(). If
> > anyone thinks we should be concerned about such an ABI change, please
> > shout quickly.
>
> That sounds problematic --- surely StdRdOptions might be something
> extensions are making use of?

So can we assume that security_barrier is the only thing to be concerned
about? If so, the attached patch should work around the issue by
placing it in the same physical location. I guess if there are modules
that add extra stuff beyond StdRdOptions, this wouldn't work, but I'm
not really sure how likely this is given that our reloptions design
hasn't proven to be the most extensible thing in the world.

--
Álvaro Herrera http://www.2ndQuadrant.com/
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