Render infinite date/timestamps as 'infinity' for json/jsonb

Commit ab14a73 raised an error in these cases and later the
behaviour was copied to jsonb. This is what the XML code, which we
then adopted, does, as the XSD types don't accept infinite values.
However, json dates and timestamps are just strings as far as json is
concerned, so there is no reason not to render these values as
'infinity'.

The json portion of this is backpatched to 9.4 where the behaviour was
introduced. The jsonb portion only affects the development branch.

Per gripe on pgsql-general.

Author: adunstan

src/backend/utils/adt/json.c

@@ -33,6 +33,9 @@
 #include "utils/typcache.h"
 #include "utils/syscache.h"
 
+/* String to output for infinite dates and timestamps */
+#define DT_INFINITY "\"infinity\""
+
 /*
  * The context of the parser is maintained by the recursive descent
  * mechanism, but is passed explicitly to the error reporting routine
@@ -1427,20 +1430,18 @@ datum_to_json(Datum val, bool is_null, StringInfo result,
 
 				date = DatumGetDateADT(val);
 
-				/* XSD doesn't support infinite values */
 				if (DATE_NOT_FINITE(date))
-					ereport(ERROR,
-							(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
-							 errmsg("date out of range"),
-							 errdetail("JSON does not support infinite date values.")));
+				{
+					/* we have to format infinity ourselves */
+					appendStringInfoString(result,DT_INFINITY);
+				}
 				else
 				{
 					j2date(date + POSTGRES_EPOCH_JDATE,
 						   &(tm.tm_year), &(tm.tm_mon), &(tm.tm_mday));
 					EncodeDateOnly(&tm, USE_XSD_DATES, buf);
+					appendStringInfo(result, "\"%s\"", buf);
 				}
-
-				appendStringInfo(result, "\"%s\"", buf);
 			}
 			break;
 		case JSONTYPE_TIMESTAMP:
@@ -1452,20 +1453,20 @@ datum_to_json(Datum val, bool is_null, StringInfo result,
 
 				timestamp = DatumGetTimestamp(val);
 
-				/* XSD doesn't support infinite values */
 				if (TIMESTAMP_NOT_FINITE(timestamp))
-					ereport(ERROR,
-							(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
-							 errmsg("timestamp out of range"),
-							 errdetail("JSON does not support infinite timestamp values.")));
+				{
+					/* we have to format infinity ourselves */
+					appendStringInfoString(result,DT_INFINITY);
+				}
 				else if (timestamp2tm(timestamp, NULL, &tm, &fsec, NULL, NULL) == 0)
+				{
 					EncodeDateTime(&tm, fsec, false, 0, NULL, USE_XSD_DATES, buf);
+					appendStringInfo(result, "\"%s\"", buf);
+				}
 				else
 					ereport(ERROR,
 							(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 							 errmsg("timestamp out of range")));
-
-				appendStringInfo(result, "\"%s\"", buf);
 			}
 			break;
 		case JSONTYPE_TIMESTAMPTZ:
@@ -1479,20 +1480,20 @@ datum_to_json(Datum val, bool is_null, StringInfo result,
 
 				timestamp = DatumGetTimestamp(val);
 
-				/* XSD doesn't support infinite values */
 				if (TIMESTAMP_NOT_FINITE(timestamp))
-					ereport(ERROR,
-							(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
-							 errmsg("timestamp out of range"),
-							 errdetail("JSON does not support infinite timestamp values.")));
+				{
+					/* we have to format infinity ourselves */
+					appendStringInfoString(result,DT_INFINITY);
+				}
 				else if (timestamp2tm(timestamp, &tz, &tm, &fsec, &tzn, NULL) == 0)
+				{
 					EncodeDateTime(&tm, fsec, true, tz, tzn, USE_XSD_DATES, buf);
+					appendStringInfo(result, "\"%s\"", buf);
+				}
 				else
 					ereport(ERROR,
 							(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 							 errmsg("timestamp out of range")));
-
-				appendStringInfo(result, "\"%s\"", buf);
 			}
 			break;
 		case JSONTYPE_JSON:

src/test/regress/expected/json.out

@@ -426,6 +426,30 @@ select to_json(timestamptz '2014-05-28 12:22:35.614298-04');
 (1 row)
 
 COMMIT;
+select to_json(date '2014-05-28');
+   to_json    
+--------------
+ "2014-05-28"
+(1 row)
+
+select to_json(date 'Infinity');
+  to_json   
+------------
+ "infinity"
+(1 row)
+
+select to_json(timestamp 'Infinity');
+  to_json   
+------------
+ "infinity"
+(1 row)
+
+select to_json(timestamptz 'Infinity');
+  to_json   
+------------
+ "infinity"
+(1 row)
+
 --json_agg
 SELECT json_agg(q)
   FROM ( SELECT $$a$$ || x AS b, y AS c,

src/test/regress/expected/json_1.out

@@ -426,6 +426,30 @@ select to_json(timestamptz '2014-05-28 12:22:35.614298-04');
 (1 row)
 
 COMMIT;
+select to_json(date '2014-05-28');
+   to_json    
+--------------
+ "2014-05-28"
+(1 row)
+
+select to_json(date 'Infinity');
+  to_json   
+------------
+ "infinity"
+(1 row)
+
+select to_json(timestamp 'Infinity');
+  to_json   
+------------
+ "infinity"
+(1 row)
+
+select to_json(timestamptz 'Infinity');
+  to_json   
+------------
+ "infinity"
+(1 row)
+
 --json_agg
 SELECT json_agg(q)
   FROM ( SELECT $$a$$ || x AS b, y AS c,

src/test/regress/sql/json.sql

@@ -111,6 +111,12 @@ SET LOCAL TIME ZONE -8;
 select to_json(timestamptz '2014-05-28 12:22:35.614298-04');
 COMMIT;
 
+select to_json(date '2014-05-28');
+
+select to_json(date 'Infinity');
+select to_json(timestamp 'Infinity');
+select to_json(timestamptz 'Infinity');
+
 --json_agg
 
 SELECT json_agg(q)