Allow width_bucket()'s "operand" input to be NaN.

The array-based variant of width_bucket() has always accepted NaN
inputs, treating them as equal but larger than any non-NaN,
as we do in ordinary comparisons.  But up to now, the four-argument
variants threw errors for a NaN operand.  This is inconsistent
and unnecessary, since we can perfectly well regard NaN as falling
after the last bucket.

We do still throw error for NaN or infinity histogram-bound inputs,
since there's no way to compute sensible bucket boundaries.

Arguably this is a bug fix, but given the lack of field complaints
I'm content to fix it in master.

Author: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Dean Rasheed <dean.a.rasheed@gmail.com>
Discussion: https://postgr.es/m/2822872.1750540911@sss.pgh.pa.us

src/backend/utils/adt/float.c

@@ -4067,8 +4067,9 @@ float84ge(PG_FUNCTION_ARGS)
  * with the specified characteristics. An operand smaller than the
  * lower bound is assigned to bucket 0. An operand greater than or equal
  * to the upper bound is assigned to an additional bucket (with number
- * count+1). We don't allow "NaN" for any of the float8 inputs, and we
+ * count+1). We don't allow the histogram bounds to be NaN or +/- infinity,
- * don't allow either of the histogram bounds to be +/- infinity.
+ * but we do allow those values for the operand (taking NaN to be larger
+ * than any other value, as we do in comparisons).
  */
 Datum
 width_bucket_float8(PG_FUNCTION_ARGS)
@@ -4084,12 +4085,11 @@ width_bucket_float8(PG_FUNCTION_ARGS)
 				(errcode(ERRCODE_INVALID_ARGUMENT_FOR_WIDTH_BUCKET_FUNCTION),
 				 errmsg("count must be greater than zero")));
 
-	if (isnan(operand) || isnan(bound1) || isnan(bound2))
+	if (isnan(bound1) || isnan(bound2))
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_ARGUMENT_FOR_WIDTH_BUCKET_FUNCTION),
-				 errmsg("operand, lower bound, and upper bound cannot be NaN")));
+				 errmsg("lower and upper bounds cannot be NaN")));
 
-	/* Note that we allow "operand" to be infinite */
 	if (isinf(bound1) || isinf(bound2))
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_ARGUMENT_FOR_WIDTH_BUCKET_FUNCTION),
@@ -4097,15 +4097,15 @@ width_bucket_float8(PG_FUNCTION_ARGS)
 
 	if (bound1 < bound2)
 	{
-		if (operand < bound1)
+		if (isnan(operand) || operand >= bound2)
-			result = 0;
-		else if (operand >= bound2)
 		{
 			if (pg_add_s32_overflow(count, 1, &result))
 				ereport(ERROR,
 						(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
 						 errmsg("integer out of range")));
 		}
+		else if (operand < bound1)
+			result = 0;
 		else
 		{
 			if (!isinf(bound2 - bound1))
@@ -4135,7 +4135,7 @@ width_bucket_float8(PG_FUNCTION_ARGS)
 	}
 	else if (bound1 > bound2)
 	{
-		if (operand > bound1)
+		if (isnan(operand) || operand > bound1)
 			result = 0;
 		else if (operand <= bound2)
 		{

src/backend/utils/adt/numeric.c

@@ -1960,8 +1960,9 @@ generate_series_numeric_support(PG_FUNCTION_ARGS)
  * with the specified characteristics. An operand smaller than the
  * lower bound is assigned to bucket 0. An operand greater than or equal
  * to the upper bound is assigned to an additional bucket (with number
- * count+1). We don't allow "NaN" for any of the numeric inputs, and we
+ * count+1). We don't allow the histogram bounds to be NaN or +/- infinity,
- * don't allow either of the histogram bounds to be +/- infinity.
+ * but we do allow those values for the operand (taking NaN to be larger
+ * than any other value, as we do in comparisons).
  */
 Datum
 width_bucket_numeric(PG_FUNCTION_ARGS)
@@ -1979,17 +1980,13 @@ width_bucket_numeric(PG_FUNCTION_ARGS)
 				(errcode(ERRCODE_INVALID_ARGUMENT_FOR_WIDTH_BUCKET_FUNCTION),
 				 errmsg("count must be greater than zero")));
 
-	if (NUMERIC_IS_SPECIAL(operand) ||
+	if (NUMERIC_IS_SPECIAL(bound1) || NUMERIC_IS_SPECIAL(bound2))
-		NUMERIC_IS_SPECIAL(bound1) ||
-		NUMERIC_IS_SPECIAL(bound2))
 	{
-		if (NUMERIC_IS_NAN(operand) ||
+		if (NUMERIC_IS_NAN(bound1) || NUMERIC_IS_NAN(bound2))
-			NUMERIC_IS_NAN(bound1) ||
-			NUMERIC_IS_NAN(bound2))
 			ereport(ERROR,
 					(errcode(ERRCODE_INVALID_ARGUMENT_FOR_WIDTH_BUCKET_FUNCTION),
-					 errmsg("operand, lower bound, and upper bound cannot be NaN")));
+					 errmsg("lower and upper bounds cannot be NaN")));
-		/* We allow "operand" to be infinite; cmp_numerics will cope */
+
 		if (NUMERIC_IS_INF(bound1) || NUMERIC_IS_INF(bound2))
 			ereport(ERROR,
 					(errcode(ERRCODE_INVALID_ARGUMENT_FOR_WIDTH_BUCKET_FUNCTION),

src/test/regress/expected/numeric.out

@@ -1464,9 +1464,21 @@ ERROR:  count must be greater than zero
 SELECT width_bucket(3.5::float8, 3.0::float8, 3.0::float8, 888);
 ERROR:  lower bound cannot equal upper bound
 SELECT width_bucket('NaN', 3.0, 4.0, 888);
-ERROR:  operand, lower bound, and upper bound cannot be NaN
+ width_bucket 
+--------------
+          889
+(1 row)
+
+SELECT width_bucket('NaN'::float8, 3.0::float8, 4.0::float8, 888);
+ width_bucket 
+--------------
+          889
+(1 row)
+
+SELECT width_bucket(0, 'NaN', 4.0, 888);
+ERROR:  lower and upper bounds cannot be NaN
 SELECT width_bucket(0::float8, 'NaN', 4.0::float8, 888);
-ERROR:  operand, lower bound, and upper bound cannot be NaN
+ERROR:  lower and upper bounds cannot be NaN
 SELECT width_bucket(2.0, 3.0, '-inf', 888);
 ERROR:  lower and upper bounds must be finite
 SELECT width_bucket(0::float8, '-inf', 4.0::float8, 888);

src/test/regress/sql/numeric.sql

@@ -869,6 +869,8 @@ SELECT width_bucket(5.0::float8, 3.0::float8, 4.0::float8, 0);
 SELECT width_bucket(5.0::float8, 3.0::float8, 4.0::float8, -5);
 SELECT width_bucket(3.5::float8, 3.0::float8, 3.0::float8, 888);
 SELECT width_bucket('NaN', 3.0, 4.0, 888);
+SELECT width_bucket('NaN'::float8, 3.0::float8, 4.0::float8, 888);
+SELECT width_bucket(0, 'NaN', 4.0, 888);
 SELECT width_bucket(0::float8, 'NaN', 4.0::float8, 888);
 SELECT width_bucket(2.0, 3.0, '-inf', 888);
 SELECT width_bucket(0::float8, '-inf', 4.0::float8, 888);