Re: Remembering bug #6123

"Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov> writes:
> Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> it needs to check the tuple's cmax [...] And that means the patch
>> will be a bit more invasive than this, because heap_update and
>> heap_delete don't return that information at present.

> I'm thinking that I could keep the test for:

> GetCurrentCommandId(false) != estate->es_output_cid

> as a "first pass". If that's true, I could use EvalPlanQualFetch()
> to find the last version of the tuple, and generate the error if the
> tuple's cmax != estate->es_output_cid. I think, although I'm not
> entirely sure, that EvalPlanQualFetch needs a little work to support
> this usage.

> Attached is a patch based on these thoughts. Is it on the right
> track? I suspect I haven't got everything covered, but thought a
> reality check was in order at this point.

You forgot to attach the patch, but the approach seems totally Rube
Goldberg to me anyway. Why not just fix heap_update/heap_delete to
return the additional information? It's not like we don't whack their
parameter lists around regularly.

Rather than having three output parameters to support the case, I'm
a bit inclined to merge them into a single-purpose struct type.
But that's mostly cosmetic.

regards, tom lane