Re: Issues with ON CONFLICT UPDATE and REINDEX CONCURRENTLY

Hello!

On Mon, Nov 3, 2025 at 12:21 AM Noah Misch <noah@leadboat.com> wrote:
> 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.

It is also affected. There is a special
reindex_concurrently_upsert_on_constraint spec in the patch.
And even a special commit (0004) to fix it :)

But yes, it happens only in the case of REINDEX.

I removed the mention of  "ON CONSTRAINT" and added a small comment
near infer_arbiter_indexes.

Doc patch is 0001, other - specs and fixes for future.

Best regards,
Mikhail.