Support domains over composite types.

This is the last major omission in our domains feature: you can now
make a domain over anything that's not a pseudotype.

The major complication from an implementation standpoint is that places
that might be creating tuples of a domain type now need to be prepared
to apply domain_check().  It seems better that unprepared code fail
with an error like "<type> is not composite" than that it silently fail
to apply domain constraints.  Therefore, relevant infrastructure like
get_func_result_type() and lookup_rowtype_tupdesc() has been adjusted
to treat domain-over-composite as a distinct case that unprepared code
won't recognize, rather than just transparently treating it the same
as plain composite.  This isn't a 100% solution to the possibility of
overlooked domain checks, but it catches most places.

In passing, improve typcache.c's support for domains (it can now cache
the identity of a domain's base type), and rewrite the argument handling
logic in jsonfuncs.c's populate_record[set]_worker to reduce duplicative
per-call lookups.

I believe this is code-complete so far as the core and contrib code go.
The PLs need varying amounts of work, which will be tackled in followup
patches.

Discussion: https://postgr.es/m/4206.1499798337@sss.pgh.pa.us

1 files changed, 9 insertions, 9 deletions

diff --git a/src/backend/parser/parse_relation.c b/src/backend/parser/parse_relation.c
index a9273affb23..ca32a37e26f 100644
--- a/src/backend/parser/parse_relation.c
+++ b/src/backend/parser/parse_relation.c
@@ -1496,7 +1496,8 @@ addRangeTableEntryForFunction(ParseState *pstate,
 						 parser_errposition(pstate, exprLocation(funcexpr))));
 		}
 
-		if (functypclass == TYPEFUNC_COMPOSITE)
+		if (functypclass == TYPEFUNC_COMPOSITE ||
+			functypclass == TYPEFUNC_COMPOSITE_DOMAIN)
 		{
 			/* Composite data type, e.g. a table's row type */
 			Assert(tupdesc);
@@ -2245,7 +2246,8 @@ expandRTE(RangeTblEntry *rte, int rtindex, int sublevels_up,
 					functypclass = get_expr_result_type(rtfunc->funcexpr,
 														&funcrettype,
 														&tupdesc);
-					if (functypclass == TYPEFUNC_COMPOSITE)
+					if (functypclass == TYPEFUNC_COMPOSITE ||
+						functypclass == TYPEFUNC_COMPOSITE_DOMAIN)
 					{
 						/* Composite data type, e.g. a table's row type */
 						Assert(tupdesc);
@@ -2765,7 +2767,8 @@ get_rte_attribute_type(RangeTblEntry *rte, AttrNumber attnum,
 															&funcrettype,
 															&tupdesc);
 
-						if (functypclass == TYPEFUNC_COMPOSITE)
+						if (functypclass == TYPEFUNC_COMPOSITE ||
+							functypclass == TYPEFUNC_COMPOSITE_DOMAIN)
 						{
 							/* Composite data type, e.g. a table's row type */
 							Form_pg_attribute att_tup;
@@ -2966,14 +2969,11 @@ get_rte_attribute_is_dropped(RangeTblEntry *rte, AttrNumber attnum)
 					if (attnum > atts_done &&
 						attnum <= atts_done + rtfunc->funccolcount)
 					{
-						TypeFuncClass functypclass;
-						Oid			funcrettype;
 						TupleDesc	tupdesc;
 
-						functypclass = get_expr_result_type(rtfunc->funcexpr,
-															&funcrettype,
-															&tupdesc);
-						if (functypclass == TYPEFUNC_COMPOSITE)
+						tupdesc = get_expr_result_tupdesc(rtfunc->funcexpr,
+														  true);
+						if (tupdesc)
 						{
 							/* Composite data type, e.g. a table's row type */
 							Form_pg_attribute att_tup;