Re: BUG #17409: Unable to alter data type of clustered column which is referenced by foreign key

On Fri, 18 Feb 2022 at 12:27, Michael Paquier <michael@paquier.xyz> wrote:
> On Fri, Feb 18, 2022 at 01:30:46AM +0800, Japin Li wrote:
> Reusing the test case at the top of the thread, this can also be
> triggered for replica identities, as of the code just at the top of
> what you have patched.  See for example:
> CREATE TABLE parent (
>   parent_field INTEGER CONSTRAINT pk_parent PRIMARY KEY);
> ALTER TABLE parent REPLICA IDENTITY USING INDEX pk_parent;
> CREATE TABLE child (
>   child_field INTEGER,
>   CONSTRAINT fk_child FOREIGN KEY (child_field) REFERENCES parent (parent_field));
> -- error here
> ALTER TABLE parent ALTER COLUMN parent_field SET DATA TYPE BIGINT;
>
> We surely should have test cases for all that.
>
> Anyway, I'd need to think more about your suggestion, but is that
> actually the best thing we can do?  In this case, we'd attempt to
> register twice an index to rebuild within
> RememberIndexForRebuilding(), for the same relation, but there is no
> need to do so.  Shouldn't we try instead to do a better job at
> scanning the pg_depend entries in ATExecAlterColumnType() and avoid
> the risk to do the same job twice?  That would take care of the
> replica identity case that I have just mentioned, and of the clustered
> index case reported upthread.


Attach a new patch to fix the replica identify case, also add test cases.

-- 
Regrads,
Japin Li.
ChengDu WenWu Information Technology Co.,Ltd.