Re: backend crash

On Mon, Apr 13, 2020 at 10:59 PM Kamil Jońca <kjonca(at)fastmail(dot)com> wrote:
> #2 0x000055f675632af4 in ExceptionalCondition (conditionName=conditionName(at)entry=0x55f6758523f8 "!(result->tdrefcount == -1)", errorType=errorType(at)entry=0x55f67568a016 "FailedAssertion",
> fileName=fileName(at)entry=0x55f675852008 "/build/postgresql-12-kUaQt8/postgresql-12-12.2/build/../src/backend/utils/cache/typcache.c", lineNumber=lineNumber(at)entry=2621) at ./build/../src/backend/utils/error/assert.c:54
> #3 0x000055f6756309ae in find_or_make_matching_shared_tupledesc (tupdesc=<optimized out>) at ./build/../src/backend/utils/cache/typcache.c:2621

This code is asserting that a TupleDesc that it found in
CurrentSession->shared_record_table is not reference counted. That's
because TupleDesc objects stored there stick around for the lifetime
of the session (= leader backend lifetime). So the question is ...
how did that thing manage to get some other value there, and what was
it? What does "frame 3", "print *result" show?