Re: [BUG] wrong FK constraint name when colliding name on ATTACH - Mailing list pgsql-hackers

Andres Freund <andres@anarazel.de> writes:
> Something here doesn't look to be quite right. Starting with this commit CI
> [1] started to fail on freebsd (stack trace [2]), and in the meson branch I've
> also seen the crash on windows (CI run[3], stack trace [4]).

The crash seems 100% reproducible if I remove the early-exit optimization
from GetForeignKeyActionTriggers:

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 53b0f3a9c1..112ca77d97 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -10591,8 +10591,6 @@ GetForeignKeyActionTriggers(Relation trigrel,
            Assert(*updateTriggerOid == InvalidOid);
            *updateTriggerOid = trgform->oid;
        }
-       if (OidIsValid(*deleteTriggerOid) && OidIsValid(*updateTriggerOid))
-           break;
    }

    if (!OidIsValid(*deleteTriggerOid))

With that in place, it's probabilistic whether the Asserts notice anything
wrong, and mostly they don't.  But there are multiple matching triggers:

regression=# select oid, tgconstraint, tgrelid,tgconstrrelid, tgtype, tgname from pg_trigger where tgconstraint =
104301;
  oid   | tgconstraint | tgrelid | tgconstrrelid | tgtype |            tgname
--------+--------------+---------+---------------+--------+-------------------------------
 104302 |       104301 |  104294 |        104294 |      9 | RI_ConstraintTrigger_a_104302
 104303 |       104301 |  104294 |        104294 |     17 | RI_ConstraintTrigger_a_104303
 104304 |       104301 |  104294 |        104294 |      5 | RI_ConstraintTrigger_c_104304
 104305 |       104301 |  104294 |        104294 |     17 | RI_ConstraintTrigger_c_104305
(4 rows)

I suspect that the filter conditions being applied are inadequate
for the case of a self-referential FK, which this evidently is
given that tgrelid and tgconstrrelid are equal.

I'd counsel dropping the early-exit optimization; it doesn't
save much I expect, and it evidently hides bugs.  Or maybe
make it conditional on !USE_ASSERT_CHECKING.

            regards, tom lane