Horton

Re: race condition in pg_class

Tom Lane <tgl@sss.pgh.pa.us>

View thread
From: Tom Lane <tgl@sss.pgh.pa.us>
To: Smolkin Grigory <smallkeen@gmail.com>
Cc: pgsql-hackers@postgresql.org
Date: 2023-10-25T18:06:45Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Replace tests of ALTER DATABASE RESET TABLESPACE.

  2. meson: Flush stdout in testwrap

  3. Fix catcache invalidation of a list entry that's being built

  4. Stop reading uninitialized memory in heap_inplace_lock().

  5. Fix use of uninitialized value in previous commit.

  6. Back-patch "Refactor code in tablecmds.c to check and process tablespace moves"

  7. Fix data loss at inplace update after heap_update().

  8. For inplace update durability, make heap_update() callers wait.

  9. Warn if LOCKTAG_TUPLE is held at commit, under debug_assertions.

  10. Don't lose partitioned table reltuples=0 after relhassubclass=f.

  11. Fix new assertion for MERGE view_name ... DO NOTHING.

  12. Remove configuration-dependent output from new inplace-inval test.

  13. AccessExclusiveLock new relations just after assigning the OID.

  14. Cope with inplace update making catcache stale during TOAST fetch.

  15. Expand comments and add an assertion in nodeModifyTable.c.

  16. Improve test coverage for changes to inplace-updated catalogs.

  17. Lock before setting relhassubclass on RELKIND_PARTITIONED_INDEX.

  18. Lock owned sequences during ALTER TABLE SET { LOGGED | UNLOGGED }.

  19. Make TAP todo_start effects the same under Meson and prove_check.

  20. Add an injection_points isolation test suite.

  21. Add wait event type "InjectionPoint", a custom type like "Extension".

  22. Create waitfuncs.c for pg_isolation_test_session_is_blocked().

  23. Rework planning and execution of UPDATE and DELETE.

Smolkin Grigory <smallkeen@gmail.com> writes:
> We are running PG13.10 and recently we have encountered what appears to be
> a bug due to some race condition between ALTER TABLE ... ADD CONSTRAINT and
> some other catalog-writer, possibly ANALYZE.
> The problem is that after successfully creating index on relation (which
> previosly didnt have any indexes), its pg_class.relhasindex remains set to
> "false", which is illegal, I think.
> Index was built using the following statement:
> ALTER TABLE "example" ADD constraint "example_pkey" PRIMARY KEY (id);

ALTER TABLE ADD CONSTRAINT would certainly have taken
AccessExclusiveLock on the "example" table, which should be sufficient
to prevent anything else from touching its pg_class row.  The only
mechanism I can think of that might bypass that is a manual UPDATE on
pg_class, which would just manipulate the row as a row without concern
for associated relation-level locks.  Any chance that somebody was
doing something like that?

			regards, tom lane