TIME

Replication

• When replicating from MariaDB Xpand to MariaDB Xpand, use row-based replication when using fractional seconds.

• When replicating from MariaDB Xpand to MariaDB Enterprise Server, fractional seconds cannot be replicated safely.

MySQL Compatibility

As with MySQL, Xpand will interpret input values supplied to DATE and TIME functions and convert them to a standard format. However, unpredictable results may occur if values are provided in other formats.

Xpand matches MySQL with the exception of:

• Xpand does not support casting a TIME to a DATETIME and returns NULL.

• Xpand does not support casting a TIME to a DATE or a DATE to a TIME.

• When converting from a DATETIME to a DATE, Xpand will discard the the time portion. MySQL will take fractional seconds into account and round the time part.

• Casting negative value to DATETIME will return a zero date. MySQL returns NULL.

• When the input to LAST_DAY is a DATETIME, MySQL will round to the nearest DATE before computing LAST_DAY where Xpand does not. For example, LAST_DAY('2013-01-31 23:59:59.999999') returns '2017-01-31' on Xpand and '2017-02-01' on MySQL.

• If an invalid format string is supplied to STR_TO_DATE, Xpand will return NULL. MySQL ignores extra characters at the end of format string.

• The results when using EXTRACT with compound units (e.g., DAY_SECOND, DAY_MICROSECOND) may exclude some of the requested units or return incorrect results.

• Output from datetime functions (e.g., NOW(), INTERVAL() FROM_UNIXTIME(), SUBTIME()) display microsecond precision by default.

• UNIX_TIMESTAMP() and FROM_UNIXTIME do not support input with fractional seconds.

• Boolean values (True, False, Null) are accepted in a DATETIME column. This matches the behavior for MySQL v5.5. MySQL v5.6 provides an error message.

• On Xpand, specifying a zero value for day, month, or year within a date will result in a zero date ('0000-00-00'). MySQL will issue an error (if the sql_mode for NO_ZERO_IN_DATE) is set, or allow zero value for the specific portion of the date.

Replication Compatibility

MariaDB recommends using row-based replication when utilizing fractional seconds.

Fractional seconds cannot be replicated safely from Xpand to MariaDB Enterprise Server.

Formats

Xpand supports multiple TIME formats, including values with fractional second precision up to 6 digits (microseconds):

CREATE TABLE time_formats_example (
   description VARCHAR(30),
   example TIME(6)
);

INSERT INTO time_formats_example VALUES
   ('HH:MM:SS', '23:45:01'),
   ('H:M:S', '1:1:1'),
   ('HHMMSS', '012345'),
   ('HMMSS.microsec', '12345.123456'),
   ('SS.microsec', '21.123456');

When a TIME value is selected, the TIME_FORMAT() function can be used to control the output format. By default, the value is returned in the HH:MM:SS.ffffff format, which is equivalent to TIME_FORMAT(<time>, '%H:%i:%S.%f'):

SELECT * FROM time_formats_example;

+----------------+-----------------+
| description    | example         |
+----------------+-----------------+
| HH:MM:SS       | 23:45:01.000000 |
| H:M:S          | 01:01:01.000000 |
| HHMMSS         | 01:23:45.000000 |
| HMMSS.microsec | 01:23:45.123456 |
| SS.microsec    | 00:00:21.123456 |
+----------------+-----------------+

Default Microsecond Precision

The default microsecond precision when unspecified is 0:

CREATE TABLE time_no_microseconds_example (
   description VARCHAR(30),
   example TIME
);

Remove Microsecond Precision

To remove microsecond precision from a TIME(6) column, cast it to TIME or TIME(0):

SELECT description,
   CONVERT(example, TIME) AS example,
   CONVERT(example, TIME(0)) AS example2
   FROM time_formats_example;

+----------------+----------+----------+
| description    | example  | example2 |
+----------------+----------+----------+
| HH:MM:SS       | 23:45:01 | 23:45:01 |
| H:M:S          | 01:01:01 | 01:01:01 |
| HHMMSS         | 01:23:45 | 01:23:45 |
| HMMSS.microsec | 01:23:45 | 01:23:45 |
| SS.microsec    | 00:00:21 | 00:00:21 |
+----------------+----------+----------+

Range

Xpand does not reject out-of-range values for the TIME data type. Out-of-range TIME values are always accepted and replaced with valid values, even when sql_mode=STRICT_TRANS_TABLES is set. If a value is too low, it is replaced with the minimum value. If a value is too high, it is replaced with the maximum value.

CREATE TABLE time_range_example (
   description VARCHAR(30),
   example TIME(6)
);

INSERT INTO time_range_example VALUES
   ('Minimum time', '-838:59:59.999999'),
   ('Maximum time', '838:59:59.999999'),
   ('Below minimum range', '-10000:00:00'),
   ('Above maximum range', '1000:00:00');

SELECT * FROM time_range_example;

+---------------------+-------------------+
| description         | example           |
+---------------------+-------------------+
| Minimum time        | -838:59:59.000000 |
| Maximum time        | 838:59:59.000000  |
| Below minimum range | -838:59:59.000000 |
| Above maximum range | 838:59:59.000000  |
+---------------------+-------------------+

Type Casting

Xpand does not support casting a DATE to a TIME and a TIME to a DATE, and returns 00:00:00 and NULL respectively:

SELECT CAST(DATE(NOW()) AS TIME);

+---------------------------+
| CAST(DATE(NOW()) AS TIME) |
+---------------------------+
| 00:00:00                  |
+---------------------------+

SELECT CONVERT(TIME(NOW()), DATE);

+----------------------------+
| CONVERT(TIME(NOW()), DATE) |
+----------------------------+
| NULL                       |
+----------------------------+

Xpand does not support casting a TIME to a DATETIME and returns NULL:

SELECT CAST(TIME(NOW()) AS DATETIME);

+-------------------------------+
| CAST(TIME(NOW()) AS DATETIME) |
+-------------------------------+
| NULL                          |
+-------------------------------+