From cc1eb6a3cccdf656df29bf5dd585a4a7068fb814 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Mon, 15 Apr 2024 12:56:56 -0400 Subject: Fix type-checking of RECORD-returning functions in FROM, redux. Commit 2ed8f9a01 intended to institute a policy that if a RangeTblFunction has a coldeflist, then the function return type is certainly RECORD, and we should use the coldeflist as the source of truth about what the columns of the record type are. When the original function has been folded to a constant, inspection of the constant might give a different answer. This situation will lead to a tuple-type-mismatch error at execution, but up until that point we need to consistently believe the coldeflist, or we'll have problems from different bits of code reaching different conclusions. expandRTE didn't get that memo though, and would try to produce a tupdesc based on the constant in this situation, leading to an assertion failure. (Desultory testing suggests that non-assert builds often manage to give the expected error, although I also saw a "cache lookup failed for type 0" error, and it seems at least possible that a crash could happen.) Some other callers of get_expr_result_type and get_expr_result_tupdesc were also being incautious about this. While none of them seem to have actual bugs, they're working harder than necessary in this case, besides which it seems safest to have an explicit policy of not using those functions on an RTE with a coldeflist. Adjust the code accordingly, and add commentary to funcapi.c about this policy. Also fix an obsolete comment that claimed "get_expr_result_type() doesn't know how to extract type info from a RECORD constant". That hasn't been true since commit d57534740. Per bug #18422 from Alexander Lakhin. As with the previous commit, back-patch to all supported branches. Discussion: https://postgr.es/m/18422-89ca86c8eac5246d@postgresql.org --- src/backend/parser/parse_relation.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) (limited to 'src/backend/parser/parse_relation.c') diff --git a/src/backend/parser/parse_relation.c b/src/backend/parser/parse_relation.c index 864ea9b0d5d..58bc222a8b9 100644 --- a/src/backend/parser/parse_relation.c +++ b/src/backend/parser/parse_relation.c @@ -2744,12 +2744,17 @@ expandRTE(RangeTblEntry *rte, int rtindex, int sublevels_up, { RangeTblFunction *rtfunc = (RangeTblFunction *) lfirst(lc); TypeFuncClass functypclass; - Oid funcrettype; - TupleDesc tupdesc; + Oid funcrettype = InvalidOid; + TupleDesc tupdesc = NULL; + + /* If it has a coldeflist, it returns RECORD */ + if (rtfunc->funccolnames != NIL) + functypclass = TYPEFUNC_RECORD; + else + functypclass = get_expr_result_type(rtfunc->funcexpr, + &funcrettype, + &tupdesc); - functypclass = get_expr_result_type(rtfunc->funcexpr, - &funcrettype, - &tupdesc); if (functypclass == TYPEFUNC_COMPOSITE || functypclass == TYPEFUNC_COMPOSITE_DOMAIN) { @@ -3375,6 +3380,10 @@ get_rte_attribute_is_dropped(RangeTblEntry *rte, AttrNumber attnum) { TupleDesc tupdesc; + /* If it has a coldeflist, it returns RECORD */ + if (rtfunc->funccolnames != NIL) + return false; /* can't have any dropped columns */ + tupdesc = get_expr_result_tupdesc(rtfunc->funcexpr, true); if (tupdesc) -- cgit v1.2.3