1 files changed, 37 insertions, 19 deletions

diff --git a/src/backend/utils/adt/cash.c b/src/backend/utils/adt/cash.c
index c787dd34191..13ec049c6a6 100644
--- a/src/backend/utils/adt/cash.c
+++ b/src/backend/utils/adt/cash.c
@@ -1032,13 +1032,8 @@ Datum
 cash_numeric(PG_FUNCTION_ARGS)
 {
 	Cash		money = PG_GETARG_CASH(0);
-	Numeric		result;
+	Datum		result;
 	int			fpoint;
-	int64		scale;
-	int			i;
-	Datum		amount;
-	Datum		numeric_scale;
-	Datum		quotient;
 	struct lconv *lconvert = PGLC_localeconv();
 
 	/* see comments about frac_digits in cash_in() */
@@ -1046,22 +1041,45 @@ cash_numeric(PG_FUNCTION_ARGS)
 	if (fpoint < 0 || fpoint > 10)
 		fpoint = 2;
 
-	/* compute required scale factor */
-	scale = 1;
-	for (i = 0; i < fpoint; i++)
-		scale *= 10;
+	/* convert the integral money value to numeric */
+	result = DirectFunctionCall1(int8_numeric, Int64GetDatum(money));
 
-	/* form the result as money / scale */
-	amount = DirectFunctionCall1(int8_numeric, Int64GetDatum(money));
-	numeric_scale = DirectFunctionCall1(int8_numeric, Int64GetDatum(scale));
-	quotient = DirectFunctionCall2(numeric_div, amount, numeric_scale);
+	/* scale appropriately, if needed */
+	if (fpoint > 0)
+	{
+		int64		scale;
+		int			i;
+		Datum		numeric_scale;
+		Datum		quotient;
+
+		/* compute required scale factor */
+		scale = 1;
+		for (i = 0; i < fpoint; i++)
+			scale *= 10;
+		numeric_scale = DirectFunctionCall1(int8_numeric,
+											Int64GetDatum(scale));
 
-	/* forcibly round to exactly the intended number of digits */
-	result = DatumGetNumeric(DirectFunctionCall2(numeric_round,
-												 quotient,
-												 Int32GetDatum(fpoint)));
+		/*
+		 * Given integral inputs approaching INT64_MAX, select_div_scale()
+		 * might choose a result scale of zero, causing loss of fractional
+		 * digits in the quotient.  We can ensure an exact result by setting
+		 * the dscale of either input to be at least as large as the desired
+		 * result scale.  numeric_round() will do that for us.
+		 */
+		numeric_scale = DirectFunctionCall2(numeric_round,
+											numeric_scale,
+											Int32GetDatum(fpoint));
+
+		/* Now we can safely divide ... */
+		quotient = DirectFunctionCall2(numeric_div, result, numeric_scale);
+
+		/* ... and forcibly round to exactly the intended number of digits */
+		result = DirectFunctionCall2(numeric_round,
+									 quotient,
+									 Int32GetDatum(fpoint));
+	}
 
-	PG_RETURN_NUMERIC(result);
+	PG_RETURN_DATUM(result);
 }
 
 /* numeric_cash()