Re: BUG #18297: Error when adding a column to a parent table with complex inheritance - Mailing list pgsql-bugs

On Wed, Jan 17, 2024 at 3:48 PM Tender Wang <tndrwang@gmail.com> wrote:

Hmm, thanks for the report.

I can repeat the aboved issue on master, even on pg10 and pg 11.

I analyzed this issue, and I found that ATExecAddColumn(), we forgot to call CommandCounterIncrement() in if (colDef->inhcount > 0) {...} branch.

So the third(a->d) updates the first(a->b->c->d) tuple.

Attached patch is my quickly fixed solution.

Indeed.  We may update the same child column multiple times, but there
is no CommandCounterIncrement between.  Nice catch and +1 to the fix.

To nitpick, how about go with the comment as

    /* Make sure the child column change is visible */

which seems clearer.

Also I think it'd be better to include a blank line before and after the
new CommandCounterIncrement statement.

Also I suggest to drop the new added tables after we've run ALTER TABLE
in the test case.

Thanks
Richard