Re: Issues with ON CONFLICT UPDATE and REINDEX CONCURRENTLY

On Tue, Oct 28, 2025 at 02:19:00AM +0100, Mihail Nikalayeu wrote:
> On Mon, Oct 27, 2025 at 7:06 PM Noah Misch <noah@leadboat.com> wrote:
> > Yes, I'm happy to push a patch documenting it.  Would you like to propose the
> > specific doc patch?  I regret lacking the bandwidth to review the fix patches.
> 
> Of course!
> 
> First version in attachment, waiting for your comment.

Thanks.  Does "ON CONFLICT ON CONSTRAINT constraint_name" avoid the problem w/
concurrent REINDEX CONCURRENTLY?  A search of the thread found no mention of
"ON CONSTRAINT".  It seems safe to assume that clause would avoid problems w/
CREATE INDEX CONCURRENTLY, but that's less certain for REINDEX.

The attached version has these changes:

- Mention ON CONSTRAINT as a workaround.  Will remove if you find or suspect
  it's not effective.
- Limit the doc change to ON CONFLICT.  I think mentioning it at the INDEX
  commands is undue emphasis.
- Use term "unique violation", a term used earlier on the same page, instead
  of "duplicate key ...".
- Remove the internals-focused point about the brief window.
- Remove some detail I considered insufficiently surprising, e.g. the point
  about "compatible with the index being built".