Re: table inheritance versus column compression and storage settings - Mailing list pgsql-hackers

From Ashutosh Bapat
Subject Re: table inheritance versus column compression and storage settings
Date
Msg-id CAExHW5s4YiD1kZDvJ6oTZ7ZRJNru-t8Zmx4Yos+ynSNcHbXz1w@mail.gmail.com
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In response to Re: table inheritance versus column compression and storage settings  (Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>)
Responses Re: table inheritance versus column compression and storage settings
List pgsql-hackers
Hi Peter and Tom,

> On Tue, Feb 20, 2024 at 3:51 PM Peter Eisentraut <peter@eisentraut.org> wrote:
> >
> > I have reverted the patch for now (and re-opened the commitfest entry).
> > We should continue to work on this and see if we can at least try to get
> > the pg_dump test coverage suitable.
> >
>

The pg_dump problems arise because we throw an error when parents have conflicting compression and storage properties. The patch that got reverted, changed this slightly by allowing a child to override parent's properties even when they conflict. It still threw an error when child didn't override and parents conflicted. I guess, MergeAttributes() raises error when it encounters parents with conflicting properties because it can not decide which of the conflicting properties the child should inherit. Instead it could just set the DEFAULT properties when parent properties conflict but child doesn't override. Thus when compression conflicts, child's compression would be set to default and when storage conflicts it will be set to the type's default storage. Child's properties when specified explicitly would override always. This will solve all the pg_dump bugs we saw with the reverted patch and also existing bug I reported earlier.

This change would break backward compatibility but I don't think anybody would rely on error being thrown when parent properties conflict.

What do you think?

--
Best Wishes,
Ashutosh Bapat

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