Allow datetime values in JsonbValue

SQL/JSON standard allows manipulation with datetime values.  So, it appears to
be convinient to allow datetime values to be represented in JsonbValue struct.
These datetime values are allowed for temporary representation only.  During
serialization datetime values are converted into strings.

SQL/JSON requires writing timestamps with timezone in the same timezone offset
as they were parsed.  This is why we allow storage of timezone offset in
JsonbValue struct.  For the same reason timezone offset argument is added to
JsonEncodeDateTime() function.

Extracted from original patch by Nikita Glukhov, Teodor Sigaev, Oleg Bartunov.
Revised by me.  Comments were adjusted by Liudmila Mantrova.

Discussion: https://postgr.es/m/fcc6fc6a-b497-f39a-923d-aa34d0c588e8%402ndQuadrant.com
Discussion: https://postgr.es/m/CAPpHfdsZgYEra_PeCLGNoXOWYx6iU-S3wF8aX0ObQUcZU%2B4XTw%40mail.gmail.com
Author: Nikita Glukhov, Teodor Sigaev, Oleg Bartunov, Alexander Korotkov, Liudmila Mantrova
Reviewed-by: Anastasia Lubennikova, Peter Eisentraut

1 files changed, 21 insertions, 0 deletions

diff --git a/src/backend/utils/adt/jsonb_util.c b/src/backend/utils/adt/jsonb_util.c
index 7e0d9de7f0c..f7f79eb965a 100644
--- a/src/backend/utils/adt/jsonb_util.c
+++ b/src/backend/utils/adt/jsonb_util.c
@@ -14,9 +14,12 @@
 #include "postgres.h"
 
 #include "catalog/pg_collation.h"
+#include "catalog/pg_type.h"
 #include "miscadmin.h"
 #include "utils/builtins.h"
+#include "utils/datetime.h"
 #include "utils/hashutils.h"
+#include "utils/jsonapi.h"
 #include "utils/jsonb.h"
 #include "utils/memutils.h"
 #include "utils/varlena.h"
@@ -244,6 +247,8 @@ compareJsonbContainers(JsonbContainer *a, JsonbContainer *b)
 						break;
 					case jbvBinary:
 						elog(ERROR, "unexpected jbvBinary value");
+					case jbvDatetime:
+						elog(ERROR, "unexpected jbvDatetime value");
 				}
 			}
 			else
@@ -1786,6 +1791,22 @@ convertJsonbScalar(StringInfo buffer, JEntry *jentry, JsonbValue *scalarVal)
 				JENTRY_ISBOOL_TRUE : JENTRY_ISBOOL_FALSE;
 			break;
 
+		case jbvDatetime:
+			{
+				char		buf[MAXDATELEN + 1];
+				size_t		len;
+
+				JsonEncodeDateTime(buf,
+								   scalarVal->val.datetime.value,
+								   scalarVal->val.datetime.typid,
+								   &scalarVal->val.datetime.tz);
+				len = strlen(buf);
+				appendToBuffer(buffer, buf, len);
+
+				*jentry = len;
+			}
+			break;
+
 		default:
 			elog(ERROR, "invalid jsonb scalar type");
 	}