From 59bc0dfe44a640c88adecc5b97def54b7355abcf Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Fri, 15 Sep 2023 16:39:27 -0400 Subject: [PATCH] Fix get_expr_result_type() to find field names for RECORD Consts. This is a back-patch of commit d57534740 ("Fix EXPLAIN of SEARCH BREADTH FIRST with a constant initial value") into pre-v14 branches. At the time I'd thought it was not needed in branches that lack the SEARCH/CYCLE feature, but that was just a failure of imagination. It's possible to demonstrate "record type has not been registered" failures in older branches too, during deparsing of views that contain references to fields of composite constants. Back-patch only the code changes, as the test cases added by d57534740 all require SEARCH/CYCLE syntax. A suitable test case will be added in the upcoming fix for bug #18077. Discussion: https://postgr.es/m/17644-3bd1f3036d6d7a16@postgresql.org Discussion: https://postgr.es/m/3607145.1694803130@sss.pgh.pa.us --- src/backend/utils/adt/ruleutils.c | 3 ++- src/backend/utils/fmgr/funcapi.c | 34 +++++++++++++++++++++++++++++++ 2 files changed, 36 insertions(+), 1 deletion(-) diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c index 2388f760704..599ed2546db 100644 --- a/src/backend/utils/adt/ruleutils.c +++ b/src/backend/utils/adt/ruleutils.c @@ -7058,7 +7058,8 @@ get_name_for_var_field(Var *var, int fieldno, /* * If it's a RowExpr that was expanded from a whole-row Var, use the - * column names attached to it. + * column names attached to it. (We could let get_expr_result_tupdesc() + * handle this, but it's much cheaper to just pull out the name we need.) */ if (IsA(var, RowExpr)) { diff --git a/src/backend/utils/fmgr/funcapi.c b/src/backend/utils/fmgr/funcapi.c index f22eef88188..ac1c75d62be 100644 --- a/src/backend/utils/fmgr/funcapi.c +++ b/src/backend/utils/fmgr/funcapi.c @@ -268,6 +268,40 @@ get_expr_result_type(Node *expr, *resultTupleDesc = BlessTupleDesc(tupdesc); return TYPEFUNC_COMPOSITE; } + else if (expr && IsA(expr, Const) && + ((Const *) expr)->consttype == RECORDOID && + !((Const *) expr)->constisnull) + { + /* + * When EXPLAIN'ing some queries with SEARCH/CYCLE clauses, we may + * need to resolve field names of a RECORD-type Const. The datum + * should contain a typmod that will tell us that. + */ + HeapTupleHeader rec; + Oid tupType; + int32 tupTypmod; + + rec = DatumGetHeapTupleHeader(((Const *) expr)->constvalue); + tupType = HeapTupleHeaderGetTypeId(rec); + tupTypmod = HeapTupleHeaderGetTypMod(rec); + if (resultTypeId) + *resultTypeId = tupType; + if (tupType != RECORDOID || tupTypmod >= 0) + { + /* Should be able to look it up */ + if (resultTupleDesc) + *resultTupleDesc = lookup_rowtype_tupdesc_copy(tupType, + tupTypmod); + return TYPEFUNC_COMPOSITE; + } + else + { + /* This shouldn't really happen ... */ + if (resultTupleDesc) + *resultTupleDesc = NULL; + return TYPEFUNC_RECORD; + } + } else { /* handle as a generic expression; no chance to resolve RECORD */