[yugabyte#5408] [YSQL] Allow datetime values in JsonbValue

Summary:
Original Postgres commit was 6dda292d4df82a9158d1acc93feecf3b84637b59

Commit message was:

    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

Test Plan: Build yugabyte db and run tests via Jenkins

Reviewers: mihnea, jason

Reviewed By: jason

Subscribers: yql

Differential Revision: https://phabricator.dev.yugabyte.com/D9548

Author: tedyu

src/postgres/src/backend/utils/adt/json.c

@@ -1506,23 +1506,23 @@ datum_to_json(Datum val, bool is_null, StringInfo result,
 			{
 				char		buf[MAXDATELEN + 1];
 
-				JsonEncodeDateTime(buf, val, DATEOID);
+				JsonEncodeDateTime(buf, val, DATEOID, NULL);
 				appendStringInfo(result, "\"%s\"", buf);
 			}
 			break;
 		case JSONTYPE_TIMESTAMP:
 			{
 				char		buf[MAXDATELEN + 1];
 
-				JsonEncodeDateTime(buf, val, TIMESTAMPOID);
+				JsonEncodeDateTime(buf, val, TIMESTAMPOID, NULL);
 				appendStringInfo(result, "\"%s\"", buf);
 			}
 			break;
 		case JSONTYPE_TIMESTAMPTZ:
 			{
 				char		buf[MAXDATELEN + 1];
 
-				JsonEncodeDateTime(buf, val, TIMESTAMPTZOID);
+				JsonEncodeDateTime(buf, val, TIMESTAMPTZOID, NULL);
 				appendStringInfo(result, "\"%s\"", buf);
 			}
 			break;
@@ -1550,10 +1550,11 @@ datum_to_json(Datum val, bool is_null, StringInfo result,
 
 /*
  * Encode 'value' of datetime type 'typid' into JSON string in ISO format using
- * optionally preallocated buffer 'buf'.
+ * optionally preallocated buffer 'buf'.  Optional 'tzp' determines time-zone
+ * offset (in seconds) in which we want to show timestamptz.
  */
 char *
-JsonEncodeDateTime(char *buf, Datum value, Oid typid)
+JsonEncodeDateTime(char *buf, Datum value, Oid typid, const int *tzp)
 {
 	if (!buf)
 		buf = palloc(MAXDATELEN + 1);
@@ -1630,11 +1631,30 @@ JsonEncodeDateTime(char *buf, Datum value, Oid typid)
 				const char *tzn = NULL;
 
 				timestamp = DatumGetTimestampTz(value);
+
+				/*
+				 * If a time zone is specified, we apply the time-zone shift,
+				 * convert timestamptz to pg_tm as if it were without a time
+				 * zone, and then use the specified time zone for converting
+				 * the timestamp into a string.
+				 */
+				if (tzp)
+				{
+					tz = *tzp;
+					timestamp -= (TimestampTz) tz * USECS_PER_SEC;
+				}
+
 				/* Same as timestamptz_out(), but forcing DateStyle */
 				if (TIMESTAMP_NOT_FINITE(timestamp))
 					EncodeSpecialTimestamp(timestamp, buf);
-				else if (timestamp2tm(timestamp, &tz, &tm, &fsec, &tzn, NULL) == 0)
+				else if (timestamp2tm(timestamp, tzp ? NULL : &tz, &tm, &fsec,
+									  tzp ? NULL : &tzn, NULL) == 0)
+				{
+					if (tzp)
+						tm.tm_isdst = 1;	/* set time-zone presence flag */
+
 					EncodeDateTime(&tm, fsec, true, tz, tzn, USE_XSD_DATES, buf);
+				}
 				else
 					ereport(ERROR,
 							(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),

src/postgres/src/backend/utils/adt/jsonb.c

@@ -206,6 +206,24 @@ JsonbTypeName(JsonbValue *jbv)
 			return "boolean";
 		case jbvNull:
 			return "null";
+		case jbvDatetime:
+			switch (jbv->val.datetime.typid)
+			{
+				case DATEOID:
+					return "date";
+				case TIMEOID:
+					return "time without time zone";
+				case TIMETZOID:
+					return "time with time zone";
+				case TIMESTAMPOID:
+					return "timestamp without time zone";
+				case TIMESTAMPTZOID:
+					return "timestamp with time zone";
+				default:
+					elog(ERROR, "unrecognized jsonb value datetime type: %d",
+						 jbv->val.datetime.typid);
+			}
+			return "unknown";
 		default:
 			elog(ERROR, "unrecognized jsonb value type: %d", jbv->type);
 			return "unknown";
@@ -805,17 +823,20 @@ datum_to_jsonb(Datum val, bool is_null, JsonbInState *result,
 				break;
 			case JSONBTYPE_DATE:
 				jb.type = jbvString;
-				jb.val.string.val = JsonEncodeDateTime(NULL, val, DATEOID);
+				jb.val.string.val = JsonEncodeDateTime(NULL, val,
+													   DATEOID, NULL);
 				jb.val.string.len = strlen(jb.val.string.val);
 				break;
 			case JSONBTYPE_TIMESTAMP:
 				jb.type = jbvString;
-				jb.val.string.val = JsonEncodeDateTime(NULL, val, TIMESTAMPOID);
+				jb.val.string.val = JsonEncodeDateTime(NULL, val,
+													   TIMESTAMPOID, NULL);
 				jb.val.string.len = strlen(jb.val.string.val);
 				break;
 			case JSONBTYPE_TIMESTAMPTZ:
 				jb.type = jbvString;
-				jb.val.string.val = JsonEncodeDateTime(NULL, val, TIMESTAMPTZOID);
+				jb.val.string.val = JsonEncodeDateTime(NULL, val,
+													   TIMESTAMPTZOID, NULL);
 				jb.val.string.len = strlen(jb.val.string.val);
 				break;
 			case JSONBTYPE_JSONCAST:

src/postgres/src/backend/utils/adt/jsonb_util.c

@@ -15,8 +15,11 @@
 
 #include "access/hash.h"
 #include "catalog/pg_collation.h"
+#include "catalog/pg_type.h"
 #include "miscadmin.h"
 #include "utils/builtins.h"
+#include "utils/datetime.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");
 	}

src/postgres/src/include/utils/jsonapi.h

@@ -161,6 +161,7 @@ extern Jsonb *transform_jsonb_string_values(Jsonb *jsonb, void *action_state,
 extern text *transform_json_string_values(text *json, void *action_state,
 							 JsonTransformStringValuesAction transform_action);
 
-extern char *JsonEncodeDateTime(char *buf, Datum value, Oid typid);
+extern char *JsonEncodeDateTime(char *buf, Datum value, Oid typid,
+								const int *tzp);
 
 #endif							/* JSONAPI_H */

src/postgres/src/include/utils/jsonb.h

@@ -241,7 +241,15 @@ enum jbvType
 	jbvArray = 0x10,
 	jbvObject,
 	/* Binary (i.e. struct Jsonb) jbvArray/jbvObject */
-	jbvBinary
+	jbvBinary,
+
+	/*
+	 * Virtual types.
+	 *
+	 * These types are used only for in-memory JSON processing and serialized
+	 * into JSON strings when outputted to json/jsonb.
+	 */
+	jbvDatetime = 0x20,
 };
 
 /*
@@ -282,11 +290,21 @@ struct JsonbValue
 			int			len;
 			JsonbContainer *data;
 		}			binary;		/* Array or object, in on-disk format */
+
+		struct
+		{
+			Datum		value;
+			Oid			typid;
+			int32		typmod;
+			int			tz;		/* Numeric time zone, in seconds, for
+								 * TimestampTz data type */
+		}			datetime;
 	}			val;
 };
 
-#define IsAJsonbScalar(jsonbval)	((jsonbval)->type >= jbvNull && \
-									 (jsonbval)->type <= jbvBool)
+#define IsAJsonbScalar(jsonbval)	(((jsonbval)->type >= jbvNull && \
+									  (jsonbval)->type <= jbvBool) || \
+									  (jsonbval)->type == jbvDatetime)
 
 /*
  * Key/value pair within an Object.