2 files changed, 31 insertions, 6 deletions

diff --git a/src/backend/parser/analyze.c b/src/backend/parser/analyze.c
index 912aab1a6f7..4b238b91951 100644
--- a/src/backend/parser/analyze.c
+++ b/src/backend/parser/analyze.c
@@ -995,17 +995,28 @@ transformInsertRow(ParseState *pstate, List *exprlist,
 
 		if (strip_indirection)
 		{
+			/*
+			 * We need to remove top-level FieldStores and SubscriptingRefs,
+			 * as well as any CoerceToDomain appearing above one of those ---
+			 * but not a CoerceToDomain that isn't above one of those.
+			 */
 			while (expr)
 			{
-				if (IsA(expr, FieldStore))
+				Expr	   *subexpr = expr;
+
+				while (IsA(subexpr, CoerceToDomain))
+				{
+					subexpr = ((CoerceToDomain *) subexpr)->arg;
+				}
+				if (IsA(subexpr, FieldStore))
 				{
-					FieldStore *fstore = (FieldStore *) expr;
+					FieldStore *fstore = (FieldStore *) subexpr;
 
 					expr = (Expr *) linitial(fstore->newvals);
 				}
-				else if (IsA(expr, SubscriptingRef))
+				else if (IsA(subexpr, SubscriptingRef))
 				{
-					SubscriptingRef *sbsref = (SubscriptingRef *) expr;
+					SubscriptingRef *sbsref = (SubscriptingRef *) subexpr;
 
 					if (sbsref->refassgnexpr == NULL)
 						break;
diff --git a/src/backend/parser/parse_target.c b/src/backend/parser/parse_target.c
index 43a7efeebed..9841894d78c 100644
--- a/src/backend/parser/parse_target.c
+++ b/src/backend/parser/parse_target.c
@@ -813,7 +813,16 @@ transformAssignmentIndirection(ParseState *pstate,
 			fstore->fieldnums = list_make1_int(attnum);
 			fstore->resulttype = baseTypeId;
 
-			/* If target is a domain, apply constraints */
+			/*
+			 * If target is a domain, apply constraints.  Notice that this
+			 * isn't totally right: the expression tree we build would check
+			 * the domain's constraints on a composite value with only this
+			 * one field populated or updated, possibly leading to an unwanted
+			 * failure.  The rewriter will merge together any subfield
+			 * assignments to the same table column, resulting in the domain's
+			 * constraints being checked only once after we've assigned to all
+			 * the fields that the INSERT or UPDATE means to.
+			 */
 			if (baseTypeId != targetTypeId)
 				return coerce_to_domain((Node *) fstore,
 										baseTypeId, baseTypeMod,
@@ -943,7 +952,12 @@ transformAssignmentSubscripts(ParseState *pstate,
 												   subscripts,
 												   rhs);
 
-	/* If target was a domain over container, need to coerce up to the domain */
+	/*
+	 * If target was a domain over container, need to coerce up to the domain.
+	 * As in transformAssignmentIndirection, this coercion is premature if the
+	 * query assigns to multiple elements of the container; but we'll fix that
+	 * during query rewrite.
+	 */
 	if (containerType != targetTypeId)
 	{
 		Oid			resulttype = exprType(result);