Re: Fast default stuff versus pg_upgrade

On 06/19/2018 12:05 PM, Andres Freund wrote:
> Hi,
>
> On 2018-06-19 11:51:16 -0400, Andrew Dunstan wrote:
>> My initial thought was that as a fallback we should disable pg_upgrade on
>> databases containing such values, and document the limitation in the docs
>> and the release notes. The workaround would be to force a table rewrite
>> which would clear them if necessary.
> I personally would say that that's not acceptable. People will start
> using fast defaults - and you can't even do anything against it! - and
> suddenly pg_upgrade won't work. But they will only notice that years
> later, after collecting terrabytes of data in such tables.

Umm, barring the case that Tom mentioned by then it would just work.
It's not the case that if they put in fast default values today they
will never be able to upgrade.

>
> If we can't fix it properly, then imo we should revert / neuter the
> feature.
>
>
>> Have we ever recommended use of pg_upgrade for some manual catalog fix after
>> release? I don't recall doing so. Certainly it hasn't been common.
> No, but why does it matter? Are you arguing we can delay pg_dump support
> for fast defaults to v12?
>

Right now I'm more or less thinking out loud, not arguing anything.

I'd at least like to see what a solution might look like before ruling
it out. I suspect I can come up with something in a day or so. The work
wouldn't be wasted.

cheers

andrew

--
Andrew Dunstan https://www.2ndQuadrant.com
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