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

2 files changed, 16 insertions, 2 deletions

diff --git a/src/test/regress/expected/numeric.out b/src/test/regress/expected/numeric.out
index 072d76ce131..93e93be5668 100644
--- a/src/test/regress/expected/numeric.out
+++ b/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);
diff --git a/src/test/regress/sql/numeric.sql b/src/test/regress/sql/numeric.sql
index b98ae27df56..640c6d92f4c 100644
--- a/src/test/regress/sql/numeric.sql
+++ b/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);