Implemented CAST from VARBINARY to DATETIME in Babelfish

Signed-off-by: yashneet vinayak <[email protected]>

contrib/babelfishpg_common/sql/datetime.sql

@@ -312,6 +312,13 @@ LANGUAGE C VOLATILE STRICT PARALLEL SAFE;
 CREATE CAST (TIMESTAMP AS DATETIME)
 WITH FUNCTION sys.timestamp2datetime(TIMESTAMP) AS ASSIGNMENT;
 
+CREATE OR REPLACE FUNCTION sys.varbinary2datetime(sys.BBF_VARBINARY)
+RETURNS DATETIME
+AS 'babelfishpg_common', 'varbinary_datetime'
+LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
+
+CREATE CAST (sys.BBF_VARBINARY AS DATETIME)
+WITH FUNCTION sys.varbinary2datetime(sys.BBF_VARBINARY) AS ASSIGNMENT;
 
 CREATE OR REPLACE FUNCTION sys.timestamptz2datetime(TIMESTAMPTZ)
 RETURNS DATETIME

contrib/babelfishpg_common/sql/upgrades/babelfish_common_helper--5.0.0--5.1.0.sql

@@ -127,5 +127,13 @@ CREATE OR REPLACE AGGREGATE sys.max(sys.money) (
     PARALLEL = SAFE
 );
 
+CREATE OR REPLACE FUNCTION sys.varbinary2datetime(sys.BBF_VARBINARY)
+RETURNS DATETIME
+AS 'babelfishpg_common', 'varbinary_datetime'
+LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
+
+CREATE CAST (sys.BBF_VARBINARY AS DATETIME)
+WITH FUNCTION sys.varbinary2datetime(sys.BBF_VARBINARY) AS ASSIGNMENT;
+
 -- Reset search_path to not affect any subsequent scripts
 SELECT set_config('search_path', trim(leading 'sys, ' from current_setting('search_path')), false);

contrib/babelfishpg_common/src/datetime.c

@@ -29,6 +29,7 @@ PG_FUNCTION_INFO_V1(datetime_recv);
 PG_FUNCTION_INFO_V1(date_datetime);
 PG_FUNCTION_INFO_V1(time_datetime);
 PG_FUNCTION_INFO_V1(timestamp_datetime);
+PG_FUNCTION_INFO_V1(varbinary_datetime);
 PG_FUNCTION_INFO_V1(timestamptz_datetime);
 PG_FUNCTION_INFO_V1(datetime_varchar);
 PG_FUNCTION_INFO_V1(varchar_datetime);
@@ -764,6 +765,69 @@ timestamp_datetime(PG_FUNCTION_ARGS)
 	PG_RETURN_TIMESTAMP(result);
 }
 
+/* 
+ * varbinary_datetime()
+ * Convert varbinary to datetime
+ */
+Datum
+varbinary_datetime(PG_FUNCTION_ARGS)
+{
+	bytea			*arg = PG_GETARG_BYTEA_PP(0);
+	int32			size = VARSIZE_ANY_EXHDR(arg);
+	int32			days;
+	int32			time_part;
+	int64			ms_value;
+	int64			usecs;
+	Timestamp		result;
+	unsigned char		*data = (unsigned char *)VARDATA_ANY(arg);
+	unsigned char		*buffer;
+
+	/* TSQL datetime is 8 bytes */
+	if (size != sizeof(int64) && size != sizeof(int32))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("invalid binary size for datetime conversion")));
+
+	buffer = (unsigned char *)palloc(size);
+	memcpy(buffer, data, size);
+
+	/* Extract days and time parts from the binary data */
+	if (size == sizeof(int32))
+	{
+		days = 0;
+		time_part = (buffer[0] << 24) | (buffer[1] << 16) | (buffer[2] << 8) | buffer[3];
+	}
+	else
+	{
+		days = (buffer[0] << 24) | (buffer[1] << 16) | (buffer[2] << 8) | buffer[3];
+		time_part = (buffer[4] << 24) | (buffer[5] << 16) | (buffer[6] << 8) | buffer[7];
+	}
+
+	/* Convert time_part to microseconds */
+	ms_value = ((int64)time_part * 10LL) / 3LL;
+	usecs = ms_value * 1000;
+
+	if (days < 0)
+	{
+		/* Handle pre-1900 dates */
+		int64 day_value = (int64) (((int64) days) & ((int64) 0xFFFFFFFF));
+		int64 total_usecs = (day_value - 0xFFFF2E46LL) * USECS_PER_DAY + usecs;
+		result = MIN_DATETIME + total_usecs;
+	}
+	else
+	{
+		/* Handle post-1900 dates */
+		int64 total_usecs = days * USECS_PER_DAY + usecs;
+		result = TSQL_DEFAULT_DATETIME + total_usecs;
+	}
+
+	pfree(buffer);
+
+	CheckDatetimeRange(result, fcinfo->context);
+
+	PG_RETURN_TIMESTAMP(result);
+}
+
 /* timestamptz_datetime()
  * Convert timestamptz to datetime
  */

contrib/babelfishpg_common/src/datetime.h

@@ -26,6 +26,8 @@
 #define MIN_DATETIME	INT64CONST(-7794489600000000)
 /* upper bond: 9999-12-31 23:59:29.999 */
 #define END_DATETIME	INT64CONST(252455615999999000)
+/* TSQL default datetime: 1900-01-01 00:00:00.000 */
+#define TSQL_DEFAULT_DATETIME	INT64CONST(-3155673600000000)
 
 extern Timestamp initializeToDefaultDatetime(void);
 /** Utility function to calculate days from '1900-01-01 00:00:00' */

test/JDBC/expected/babel_datetime-vu-prepare.out

@@ -45,3 +45,33 @@ INSERT INTO babel_datetime_vu_prepare_testing VALUES('2020-03-14')
 go
 ~~ROW COUNT: 1~~
 
+INSERT INTO babel_datetime_vu_prepare_testing VALUES(0x0000B022)
+go
+~~ROW COUNT: 1~~
+
+INSERT INTO babel_datetime_vu_prepare_testing VALUES(0x0000B02200EF28C0)
+go
+~~ROW COUNT: 1~~
+
+INSERT INTO babel_datetime_vu_prepare_testing VALUES(0x00008EE700C5C100)
+go
+~~ROW COUNT: 1~~
+
+INSERT INTO babel_datetime_vu_prepare_testing VALUES(0xFFFF2E4600000000)
+go
+~~ROW COUNT: 1~~
+
+INSERT INTO babel_datetime_vu_prepare_testing VALUES(0x0000B02200EF28C1)
+go
+~~ROW COUNT: 1~~
+
+INSERT INTO babel_datetime_vu_prepare_testing VALUES(0x002D247F018B81FF)
+go
+~~ROW COUNT: 1~~
+
+INSERT INTO babel_datetime_vu_prepare_testing VALUES(0x002D247F018B8200)
+go
+~~ERROR (Code: 517)~~
+
+~~ERROR (Message: data out of range for datetime)~~
+