diff --git a/src/backend/utils/adt/numeric.c b/src/backend/utils/adt/numeric.c
index 1bfa29e1b280ba8aa1025e1e71dc8490094cda4a..1667d8093f1b70dd5fd15ed9e369bce802a07d18 100644
--- a/src/backend/utils/adt/numeric.c
+++ b/src/backend/utils/adt/numeric.c
@@ -5789,9 +5789,15 @@ mul_var(NumericVar *var1, NumericVar *var2, NumericVar *result,
* to avoid normalizing carries immediately.
*
* maxdig tracks the maximum possible value of any dig[] entry; when this
- * threatens to exceed INT_MAX, we take the time to propagate carries. To
- * avoid overflow in maxdig itself, it actually represents the max
- * possible value divided by NBASE-1.
+ * threatens to exceed INT_MAX, we take the time to propagate carries.
+ * Furthermore, we need to ensure that overflow doesn't occur during the
+ * carry propagation passes either. The carry values could be as much as
+ * INT_MAX/NBASE, so really we must normalize when digits threaten to
+ * exceed INT_MAX - INT_MAX/NBASE.
+ *
+ * To avoid overflow in maxdig itself, it actually represents the max
+ * possible value divided by NBASE-1, ie, at the top of the loop it is
+ * known that no dig[] entry exceeds maxdig * (NBASE-1).
*/
dig = (int *) palloc0(res_ndigits * sizeof(int));
maxdig = 0;
@@ -5806,7 +5812,7 @@ mul_var(NumericVar *var1, NumericVar *var2, NumericVar *result,
/* Time to normalize? */
maxdig += var1digit;
- if (maxdig > INT_MAX / (NBASE - 1))
+ if (maxdig > (INT_MAX - INT_MAX / NBASE) / (NBASE - 1))
{
/* Yes, do it */
carry = 0;
diff --git a/src/test/regress/expected/numeric.out b/src/test/regress/expected/numeric.out
index e6ee548e7c0b4d4c1489f599d1261185f5fc2306..c1886fd6635e3ea64e7b3e4f8d1f2ac4a0017839 100644
--- a/src/test/regress/expected/numeric.out
+++ b/src/test/regress/expected/numeric.out
@@ -1333,6 +1333,33 @@ SELECT * FROM num_input_test;
NaN
(7 rows)
+--
+-- Test some corner cases for multiplication
+--
+select 4790999999999999999999999999999999999999999999999999999999999999999999999999999999999999 * 9999999999999999999999999999999999999999999999999999999999999999999999999999999999999999;
+ ?column?
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ 47909999999999999999999999999999999999999999999999999999999999999999999999999999999999985209000000000000000000000000000000000000000000000000000000000000000000000000000000000001
+(1 row)
+
+select 4789999999999999999999999999999999999999999999999999999999999999999999999999999999999999 * 9999999999999999999999999999999999999999999999999999999999999999999999999999999999999999;
+ ?column?
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ 47899999999999999999999999999999999999999999999999999999999999999999999999999999999999985210000000000000000000000000000000000000000000000000000000000000000000000000000000000001
+(1 row)
+
+select 4770999999999999999999999999999999999999999999999999999999999999999999999999999999999999 * 9999999999999999999999999999999999999999999999999999999999999999999999999999999999999999;
+ ?column?
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ 47709999999999999999999999999999999999999999999999999999999999999999999999999999999999985229000000000000000000000000000000000000000000000000000000000000000000000000000000000001
+(1 row)
+
+select 4769999999999999999999999999999999999999999999999999999999999999999999999999999999999999 * 9999999999999999999999999999999999999999999999999999999999999999999999999999999999999999;
+ ?column?
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ 47699999999999999999999999999999999999999999999999999999999999999999999999999999999999985230000000000000000000000000000000000000000000000000000000000000000000000000000000000001
+(1 row)
+
--
-- Test some corner cases for division
--
diff --git a/src/test/regress/sql/numeric.sql b/src/test/regress/sql/numeric.sql
index 982287c33ad602001a97da5e67b464c9a59c8e64..49ec478bd971ab96c0e3465f80ff2153ad3f9807 100644
--- a/src/test/regress/sql/numeric.sql
+++ b/src/test/regress/sql/numeric.sql
@@ -821,6 +821,18 @@ INSERT INTO num_input_test(n1) VALUES (' N aN ');
SELECT * FROM num_input_test;
+--
+-- Test some corner cases for multiplication
+--
+
+select 4790999999999999999999999999999999999999999999999999999999999999999999999999999999999999 * 9999999999999999999999999999999999999999999999999999999999999999999999999999999999999999;
+
+select 4789999999999999999999999999999999999999999999999999999999999999999999999999999999999999 * 9999999999999999999999999999999999999999999999999999999999999999999999999999999999999999;
+
+select 4770999999999999999999999999999999999999999999999999999999999999999999999999999999999999 * 9999999999999999999999999999999999999999999999999999999999999999999999999999999999999999;
+
+select 4769999999999999999999999999999999999999999999999999999999999999999999999999999999999999 * 9999999999999999999999999999999999999999999999999999999999999999999999999999999999999999;
+
--
-- Test some corner cases for division
--