Support infinity and -infinity in the numeric data type.

Add infinities that behave the same as they do in the floating-point
data types.  Aside from any intrinsic usefulness these may have,
this closes an important gap in our ability to convert floating
values to numeric and/or replace float-based APIs with numeric.

The new values are represented by bit patterns that were formerly
not used (although old code probably would take them for NaNs).
So there shouldn't be any pg_upgrade hazard.

Patch by me, reviewed by Dean Rasheed and Andrew Gierth

Discussion: https://postgr.es/m/606717.1591924582@sss.pgh.pa.us

2 files changed, 8 insertions, 7 deletions

diff --git a/contrib/jsonb_plperl/jsonb_plperl.c b/contrib/jsonb_plperl/jsonb_plperl.c
index ed361efbe20..b81ba54b809 100644
--- a/contrib/jsonb_plperl/jsonb_plperl.c
+++ b/contrib/jsonb_plperl/jsonb_plperl.c
@@ -227,10 +227,8 @@ SV_to_JsonbValue(SV *in, JsonbParseState **jsonb_state, bool is_elem)
 				/*
 				 * jsonb doesn't allow infinity or NaN (per JSON
 				 * specification), but the numeric type that is used for the
-				 * storage accepts NaN, so we have to prevent it here
-				 * explicitly.  We don't really have to check for isinf()
-				 * here, as numeric doesn't allow it and it would be caught
-				 * later, but it makes for a nicer error message.
+				 * storage accepts those, so we have to reject them here
+				 * explicitly.
 				 */
 				if (isinf(nval))
 					ereport(ERROR,
diff --git a/contrib/jsonb_plpython/jsonb_plpython.c b/contrib/jsonb_plpython/jsonb_plpython.c
index e09308daf07..836c1787706 100644
--- a/contrib/jsonb_plpython/jsonb_plpython.c
+++ b/contrib/jsonb_plpython/jsonb_plpython.c
@@ -387,14 +387,17 @@ PLyNumber_ToJsonbValue(PyObject *obj, JsonbValue *jbvNum)
 	pfree(str);
 
 	/*
-	 * jsonb doesn't allow NaN (per JSON specification), so we have to prevent
-	 * it here explicitly.  (Infinity is also not allowed in jsonb, but
-	 * numeric_in above already catches that.)
+	 * jsonb doesn't allow NaN or infinity (per JSON specification), so we
+	 * have to reject those here explicitly.
 	 */
 	if (numeric_is_nan(num))
 		ereport(ERROR,
 				(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
 				 errmsg("cannot convert NaN to jsonb")));
+	if (numeric_is_inf(num))
+		ereport(ERROR,
+				(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
+				 errmsg("cannot convert infinity to jsonb")));
 
 	jbvNum->type = jbvNumeric;
 	jbvNum->val.numeric = num;