Re: Logical Decoding and HeapTupleSatisfiesVacuum assumptions

On 01/19/2018 08:33 PM, Robert Haas wrote:
> On Fri, Jan 19, 2018 at 2:16 PM, Tomas Vondra
> <tomas(dot)vondra(at)2ndquadrant(dot)com> wrote:
>> I think an important piece of this puzzle is that we only really care
>> about catalog changes made in a transaction that aborts after doing some
>> additional changes, with that catalog tuple in place. Because only then
>> we actually need that catalog tuple in order to interpret the changes.
>>
>> AFAICS that guarantees the catalog changes were not interrupted half-way
>> through, leaving some of the catalogs in inconsistent state.
>
> Yeah, that may be true, and I alluded to it in the part you didn't
> quote. However, it doesn't help with the second problem I mentioned,
> which looks to me to be a fatal problem.
>

Ah, OK - I didn't realize "using a command ID value that was reached
prior to the error" refers to this scenario.

Regarding the HOT issue - I have to admit I don't quite see why A2
wouldn't be reachable through the index, but that's likely due to my
limited knowledge of the HOT internals.

regards

--
Tomas Vondra http://www.2ndQuadrant.com
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