Re: [PATCH] Preserve replication origin OIDs in pg_upgrade

Hi Ajin,

Shveta's right, sorry for the noise -- git am --3way applies v10 cleanly on
HEAD (9d1188f298) and it builds. "git apply --check" was tripping on the
shifted pg_proc.dat hunk on my end.

Confirmed Shveta's (6), and it's a crash, not just a bad read:

cluster->sub_retain_dead_tuples = (strcmp(PQgetvalue(res, 0,
i_retain_dead_tuples), "t") == 0);

With no subscriptions the < 1900 query returns zero rows, PQgetvalue(res, 0,
...) returns NULL for a nonexistent row, and the strcmp segfaults (reproduced
with a small libpq program). Upgrading a v17/v18 cluster that has no
subscriptions hits it. Shveta's "SELECT false" fix is right.

A few more comments from re-reading v10:

1) The doc hunk updates this sentence:

- Commit timestamps and origin data are not preserved during
the upgrade.
+ Commit timestamps are not preserved during the upgrade.

but the twin comment in pg_upgrade.c (~line 222) is left unchanged and needs
the same edit:

* upgrade. Additionally, commit timestamps and origin data are not
* preserved during the upgrade. So, even after creating the slot, the

2) dumpReplicationOrigins:

+ appendPQExpBufferStr(buf,
+ "SELECT o.*, os.remote_lsn "
+ "FROM pg_catalog.pg_replication_origin o "
+ "LEFT OUTER JOIN pg_catalog.pg_replication_origin_status os ON
o.roident = os.local_id ");

No ORDER BY, so the output order is whatever the heap returns; every other
query in pg_dumpall.c has one. ORDER BY o.roident would keep the dump stable.

3) Trivia: trailing space in the section header --

+ fprintf(OPF, "--\n-- Replication Origins \n--\n\n");

and a stray blank line at the end of replorigin_create_with_id():

+ false /* WAL log */);
+ }
+
+}

Also, per my earlier mail, the >= 905 / >= 90500 gates can come out now that
14d8418083 raised the pg_upgrade floor to v10.

Thanks,
Rui