reindex concurrently and two toast indexes

Forking old, long thread:
https://www.postgresql.org/message-id/36712441546604286%40sas1-890ba5c2334a.qloud-c.yandex.net
On Fri, Jan 04, 2019 at 03:18:06PM +0300, Sergei Kornilov wrote:
> About reindex invalid indexes - i found one good question in archives [1]: how about toast indexes?
> I check it now, i am able drop invalid toast index, but i can not drop reduntant valid index.
> Reproduce:
> session 1: begin; select from test_toast ... for update;
> session 2: reindex table CONCURRENTLY test_toast ;
> session 2: interrupt by ctrl+C
> session 1: commit
> session 2: reindex table test_toast ;
> and now we have two toast indexes. DROP INDEX is able to remove only invalid ones. Valid index gives "ERROR: permission denied: "pg_toast_16426_index_ccnew" is a system catalog"
> [1]: https://www.postgresql.org/message-id/CAB7nPqT%2B6igqbUb59y04NEgHoBeUGYteuUr89AKnLTFNdB8Hyw%40mail.gmail.com

It looks like this was never addressed.

I noticed a ccnew toast index sitting around since October - what do I do with it ?

ts=# DROP INDEX pg_toast.pg_toast_463881620_index_ccnew;
ERROR: permission denied: "pg_toast_463881620_index_ccnew" is a system catalog

--
Justin