Convert HEXTORAW value to TIMESTAMP - oracle

Question

I am working on some analysis tools and I have a specific situation where I have a value that is represented using the HEXTORAW Oracle function as follows:
HEXTORAW('7876031b0d233900786450')
This value represents what would otherwise be written as TO_TIMSTAMP('2018-03-27 12:34:56.00789'). So far I have found two ways to attempt to convert this HEXTORAW value:
Using dbms_stats.convert_raw_to_date
Using dbms_stats.convert_raw_value in a PL/SQL block
In both cases, the return value doesn't have the fractal seconds portion of the timestamp and I suspect this is likely due to the underlying calls relying on a DATE data type rather than a true TIMESTAMP data type.
Does anyone know if there is another PL/SQL package function that could be used to decode the raw value back to a complete timestamp that includes the fractal seconds?

Answer 1

There is not a function that converts a hex-string to a TIMESTAMP but you can easily calculate the TIMESTAMP value.
Convert the first 7 bytes to a DATE and then cast it to a TIMESTAMP(9) (which will have fractional seconds of 0) and then you can convert the last 4 bytes to a number, which represents the number of nanoseconds and then add that to the timestamp:
SELECT CAST(
DBMS_STATS.CONVERT_RAW_TO_DATE(HEXTORAW(SUBSTR(hex_value,1,14)))
AS TIMESTAMP(9)
)
+ INTERVAL '1' SECOND(9)
* TO_NUMBER(HEXTORAW(SUBSTR(hex_value,15,8)), 'XXXXXXXX') / 1e9
AS timestamp_val,
hex_value
FROM (
SELECT '7876031b0d233900786450' AS hex_value FROM DUAL
)
Outputs:
TIMESTAMP_VAL
HEX_VALUE
2018-03-27 12:34:56.007890000
7876031b0d233900786450
and
CREATE TABLE table_name (value TIMESTAMP(9));
INSERT INTO table_name (value) VALUES (TIMESTAMP '2018-03-27 12:34:56.007890000');
SELECT value, DUMP(value,16) FROM table_name
Outputs:
VALUE
DUMP(VALUE,16)
2018-03-27 12:34:56.007890000
Typ=180 Len=11: 78,76,3,1b,d,23,39,0,78,64,50
Which has the same timestamp and same byte values.
If you want to wrap it into a function then:
CREATE FUNCTION hex_to_timestamp(
hex_value IN VARCHAR2
) RETURN TIMESTAMP DETERMINISTIC
IS
BEGIN
RETURN CAST(
DBMS_STATS.CONVERT_RAW_TO_DATE(HEXTORAW(SUBSTR(hex_value,1,14)))
AS TIMESTAMP
)
+ INTERVAL '1' SECOND
* TO_NUMBER(HEXTORAW(SUBSTR(hex_value,15,8)), 'XXXXXXXX') / 1e9;
END;
/
db<>fiddle here
Update
Perhaps the "simplest" method is to use something that will already convert a byte string to a timestamp. In this case, the Java class oracle.sql.TIMESTAMP has a constructor that takes a byte array (and there is a similar constructor for oracle.sql.TIMESTAMPTZ).
Therefore, if you have Java enabled in the database, you can use a small class to convert the hex-string to a byte array and then to wrap the constructors in functions:
CREATE AND COMPILE JAVA SOURCE NAMED HexToTimestampConverter AS
import oracle.sql.TIMESTAMP;
import oracle.sql.TIMESTAMPTZ;
public class HexToTimestampConverter {
public static byte[] hexStringToByteArray(String s) {
int len = s.length();
byte[] data = new byte[len / 2];
for (int i = 0; i < len; i += 2) {
data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) << 4)
+ Character.digit(s.charAt(i+1), 16));
}
return data;
}
public static TIMESTAMP hexToTimestamp(final String hex)
{
return new TIMESTAMP(hexStringToByteArray(hex));
}
public static TIMESTAMPTZ hexToTimestamptz(final String hex)
{
return new TIMESTAMPTZ(hexStringToByteArray(hex));
}
}
Then you can create an SQL function to call the Java code:
CREATE FUNCTION hex_to_timestamp( in_value IN VARCHAR2 ) RETURN TIMESTAMP
AS LANGUAGE JAVA NAME 'HexToTimestampConverter.hexToTimestamp(java.lang.String) return oracle.sql.TIMESTAMP';
/
And for TIMESTAMP WITH TIME ZONE:
CREATE FUNCTION hex_to_timestamptz( in_value IN VARCHAR2 ) RETURN TIMESTAMP WITH TIME ZONE
AS LANGUAGE JAVA NAME 'HexToTimestampConverter.hexToTimestamptz(java.lang.String) return oracle.sql.TIMESTAMPTZ';
/
(Note: you probably want to add some error checking to check that the string is hexadecimal and of the correct length.)
db<>fiddle here