Merge #34412

34412: sql: JSON-ify timestamps using RFC3339 format r=bobvawter a=bobvawter

Currently, when converting a timestamp value to a JSON string, we use
CockroachDB's customary string format, which is RFC3339 without the T separator.
This creates some compatibility problems with JSON consumers which expect to
receive exactly RFC3339-formatted timestamp value.

The output in the logictest has been cross-checked against a PostgreSQL 10
database.

Fixes #34372

Release note (sql change): Formatting of timestamps as JSON strings has been
changed to always use the RFC3339 format instead of Cockroach's customary
format. Users can now expect to see a `T` separator instead of a space between
the date and time components.

Co-authored-by: Bob Vawter <[email protected]>

pkg/sql/logictest/testdata/logic_test/json_builtins

@@ -184,12 +184,17 @@ SELECT to_json(ARRAY[[1, 2], [3, 4]])
 query T
 SELECT to_json('2014-05-28 12:22:35.614298'::TIMESTAMP)
 ----
-"2014-05-28 12:22:35.614298+00:00"
+"2014-05-28T12:22:35.614298"
 
 query T
 SELECT to_json('2014-05-28 12:22:35.614298-04'::TIMESTAMPTZ)
 ----
-"2014-05-28 12:22:35.614298-04:00"
+"2014-05-28T12:22:35.614298-04:00"
+
+query T
+SELECT to_json('2014-05-28 12:22:35.614298-04'::TIMESTAMP)
+----
+"2014-05-28T12:22:35.614298"
 
 query T
 SELECT to_json('2014-05-28'::DATE)
@@ -279,12 +284,17 @@ SELECT to_jsonb(ARRAY[[1, 2], [3, 4]])
 query T
 SELECT to_jsonb('2014-05-28 12:22:35.614298'::TIMESTAMP)
 ----
-"2014-05-28 12:22:35.614298+00:00"
+"2014-05-28T12:22:35.614298"
 
 query T
 SELECT to_jsonb('2014-05-28 12:22:35.614298-04'::TIMESTAMPTZ)
 ----
-"2014-05-28 12:22:35.614298-04:00"
+"2014-05-28T12:22:35.614298-04:00"
+
+query T
+SELECT to_jsonb('2014-05-28 12:22:35.614298-04'::TIMESTAMP)
+----
+"2014-05-28T12:22:35.614298"
 
 query T
 SELECT to_jsonb('2014-05-28'::DATE)

pkg/sql/sem/tree/datum.go

@@ -2455,7 +2455,16 @@ func AsJSON(d Datum) (json.JSON, error) {
 			builder.Add(fmt.Sprintf("f%d", i+1), j)
 		}
 		return builder.Build(), nil
-	case *DTimestamp, *DTimestampTZ, *DDate, *DUuid, *DOid, *DInterval, *DBytes, *DIPAddr, *DTime, *DBitArray:
+	case *DTimestampTZ:
+		// Our normal timestamp-formatting code uses a variation on RFC 3339,
+		// without the T separator. This causes some compatibility problems
+		// with certain JSON consumers, so we'll use an alternate formatting
+		// path here to maintain consistency with PostgreSQL.
+		return json.FromString(t.Time.Format(time.RFC3339Nano)), nil
+	case *DTimestamp:
+		// This is RFC3339Nano, but without the TZ fields.
+		return json.FromString(t.UTC().Format("2006-01-02T15:04:05.999999999")), nil
+	case *DDate, *DUuid, *DOid, *DInterval, *DBytes, *DIPAddr, *DTime, *DBitArray:
 		return json.FromString(AsStringWithFlags(t, FmtBareStrings)), nil
 	default:
 		if d == DNull {