@@ -2443,14 +2443,14 @@ ExecInitArrayRef(ExprEvalStep *scratch, ArrayRef *aref, PlanState *parent,
24432443 * refassgnexpr is itself a FieldStore or ArrayRef that needs to
24442444 * obtain and modify the previous value of the array element or slice
24452445 * being replaced. If so, we have to extract that value from the
2446- * array and pass it down via theCaseTextExpr mechanism. It's safe
2446+ * array and pass it down via theCaseTestExpr mechanism. It's safe
24472447 * to reuse the CASE mechanism because there cannot be a CASE between
24482448 * here and where the value would be needed, and an array assignment
24492449 * can't be within a CASE either. (So saving and restoring
24502450 * innermost_caseval is just paranoia, but let's do it anyway.)
24512451 *
24522452 * Since fetching the old element might be a nontrivial expense, do it
2453- * only if the argumentappears to actuallyneed it.
2453+ * only if the argument actuallyneeds it.
24542454 */
24552455if (isAssignmentIndirectionExpr (aref -> refassgnexpr ))
24562456{
@@ -2506,10 +2506,16 @@ ExecInitArrayRef(ExprEvalStep *scratch, ArrayRef *aref, PlanState *parent,
25062506
25072507/*
25082508 * Helper for preparing ArrayRef expressions for evaluation: is expr a nested
2509- * FieldStore or ArrayRef thatmight need the old element value passed down?
2509+ * FieldStore or ArrayRef thatneeds the old element value passed down?
25102510 *
25112511 * (We could use this in FieldStore too, but in that case passing the old
25122512 * value is so cheap there's no need.)
2513+ *
2514+ * Note: it might seem that this needs to recurse, but it does not; the
2515+ * CaseTestExpr, if any, will be directly the arg or refexpr of the top-level
2516+ * node. Nested-assignment situations give rise to expression trees in which
2517+ * each level of assignment has its own CaseTestExpr, and the recursive
2518+ * structure appears within the newvals or refassgnexpr field.
25132519 */
25142520static bool
25152521isAssignmentIndirectionExpr (Expr * expr )