If you create a partitioned table in the obvious way, partcollation ends up 0:
rhaas=# create table foo (a int, b text) partition by list (a);
CREATE TABLE
rhaas=# select * from pg_partitioned_table;partrelid | partstrat | partnatts | partattrs | partclass |
partcollation | partexprs
-----------+-----------+-----------+-----------+-----------+---------------+----------- 16420 | l |
1| 1 | 1978 | 0 |
(1 row)
You could argue that 0 is an OK value there; offhand, I'm not sure
about that. But there's nothing in
https://www.postgresql.org/docs/10/static/catalog-pg-partitioned-table.html
which indicates that some entries can be 0 rather than a valid
collation OID. And this is definitely not OK:
rhaas=# select * from pg_depend where objid = 16420;classid | objid | objsubid | refclassid | refobjid | refobjsubid |
deptype
---------+-------+----------+------------+----------+-------------+--------- 1259 | 16420 | 0 | 2615 |
2200 | 0 | n 1259 | 16420 | 0 | 3456 | 0 | 0 | n
(2 rows)
We shouldn't be storing a dependency on non-existing collation 0.
I'm not sure whether the bug here is that we should have a valid
collation OID there rather than 0, or whether the bug is that we
shouldn't be recording a dependency on anything other than a real
collation OID, but something about this is definitely not right.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company