Dependencies for partitioned indexes are still a mess

I've been experimenting with trying to dump-and-restore the
regression database, which is a test case that for some reason
we don't cover in the buildfarm (pg_upgrade is not the same thing).
It seems like the dependency choices we've made for partitioned
indexes are a complete failure for this purpose.

Setup:

1. make installcheck
2. Work around the bug complained of at [1]:
psql regression -c 'drop table gtest30_1, gtest1_1'
3. pg_dump -Fc regression >regression.dump

Issue #1: "--clean" does not work

1. createdb r2
2. pg_restore -d r2 regression.dump
3. pg_restore --clean -d r2 regression.dump

pg_restore: while PROCESSING TOC:
pg_restore: from TOC entry 6606; 1259 35458 INDEX idxpart32_a_idx postgres
pg_restore: error: could not execute query: ERROR: cannot drop index public.idxpart32_a_idx because index public.idxpart3_a_idx requires it
HINT: You can drop index public.idxpart3_a_idx instead.
Command was: DROP INDEX public.idxpart32_a_idx;
pg_restore: from TOC entry 6605; 1259 35454 INDEX idxpart31_a_idx postgres
pg_restore: error: could not execute query: ERROR: cannot drop index public.idxpart31_a_idx because index public.idxpart3_a_idx requires it
HINT: You can drop index public.idxpart3_a_idx instead.
Command was: DROP INDEX public.idxpart31_a_idx;
...
pg_restore: from TOC entry 6622; 2606 35509 CONSTRAINT pk52 pk52_pkey postgres
pg_restore: error: could not execute query: ERROR: cannot drop inherited constraint "pk52_pkey" of relation "pk52"
Command was: ALTER TABLE ONLY regress_indexing.pk52 DROP CONSTRAINT pk52_pkey;
pg_restore: from TOC entry 6620; 2606 35504 CONSTRAINT pk51 pk51_pkey postgres
pg_restore: error: could not execute query: ERROR: cannot drop inherited constraint "pk51_pkey" of relation "pk51"
Command was: ALTER TABLE ONLY regress_indexing.pk51 DROP CONSTRAINT pk51_pkey;
pg_restore: from TOC entry 6618; 2606 35502 CONSTRAINT pk5 pk5_pkey postgres
pg_restore: error: could not execute query: ERROR: cannot drop inherited constraint "pk5_pkey" of relation "pk5"
Command was: ALTER TABLE ONLY regress_indexing.pk5 DROP CONSTRAINT pk5_pkey;
...

(There seem to be some other problems as well, but most of the 54 complaints
are related to partitioned indexes/constraints.)

Issue #2: parallel restore does not work

1. dropdb r2; createdb r2
2. pg_restore -j8 -d r2 regression.dump

This is fairly timing-dependent, but some attempts fail with messages
like

pg_restore: while PROCESSING TOC:
pg_restore: from TOC entry 6684; 2606 29166 FK CONSTRAINT fk fk_a_fkey postgres
pg_restore: error: could not execute query: ERROR: there is no unique constraint matching given keys for referenced table "pk"
Command was: ALTER TABLE fkpart3.fk
ADD CONSTRAINT fk_a_fkey FOREIGN KEY (a) REFERENCES fkpart3.pk(a);

The problem here seems to be that some commands like this:

ALTER INDEX fkpart3.pk5_pkey ATTACH PARTITION fkpart3.pk52_pkey;

are not executed soon enough, indicating that we lack dependencies
that would guarantee the restore order.

I have not analyzed these issues in any detail -- they're just bugs
I tripped over while testing parallel pg_restore. In particular
I do not know if #1 and #2 have the same root cause.

regards, tom lane

[1] https://www.postgresql.org/message-id/3169466.1594841366%40sss.pgh.pa.us