root@271d43d01a39:~# mariadb

Welcome to the MariaDB monitor.  Commands end with ; or \g.

Your MariaDB connection id is 32

Server version: 11.0.2-MariaDB-debug MariaDB Server

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MariaDB [(none)]> create database debug;

Query OK, 1 row affected (0.001 sec)

MariaDB [(none)]> use debug

Database changed

MariaDB [debug]> CREATE TABLE t1(col TIME(3))ENGINE=Columnstore;

Query OK, 0 rows affected (14.087 sec)

MariaDB [debug]> INSERT INTO t1 VALUES('00:00:40.991');

Query OK, 1 row affected (1.074 sec)

MariaDB [debug]> SELECT TIME_TO_SEC('00:00:40.991') FROM t1;

+-----------------------------+

| TIME_TO_SEC('00:00:40.991') |

+-----------------------------+

|                      40.991 |

+-----------------------------+

1 row in set (0.154 sec)

MariaDB [debug]> SELECT TIME_TO_SEC('00:00:40.99') FROM t1;

+----------------------------+

| TIME_TO_SEC('00:00:40.99') |

+----------------------------+

|                      40.99 |

+----------------------------+

1 row in set (0.016 sec)

MariaDB [debug]> SELECT col, TIME_TO_SEC(col) FROM t1;

+--------------+------------------+

| col          | TIME_TO_SEC(col) |

+--------------+------------------+

| 00:00:40.991 |           40.000 |

+--------------+------------------+

1 row in set (0.015 sec)

MariaDB [(none)]> create database debug;

Query OK, 1 row affected (0.001 sec)

MariaDB [(none)]> use debug;

Database changed

MariaDB [debug]> CREATE TABLE t1(col TIME(3))ENGINE=Columnstore;

Query OK, 0 rows affected (13.020 sec)

MariaDB [debug]> INSERT INTO t1 VALUES('00:00:40.991');

^[[Query OK, 1 row affected (3.277 sec)

MariaDB [debug]> SELECT TIME_TO_SEC('00:00:40.991') FROM t1;

+-----------------------------+

| TIME_TO_SEC('00:00:40.991') |

+-----------------------------+

|                      40.991 |

+-----------------------------+

1 row in set (0.232 sec)

MariaDB [debug]> SELECT TIME_TO_SEC('00:00:40.99') FROM t1;

+----------------------------+

| TIME_TO_SEC('00:00:40.99') |

+----------------------------+

|                      40.99 |

+----------------------------+

1 row in set (0.014 sec)

MariaDB [debug]> SELECT col, TIME_TO_SEC(col) FROM t1;

+--------------+------------------+

| col          | TIME_TO_SEC(col) |

+--------------+------------------+

| 00:00:40.991 |           40.000 |

+--------------+------------------+

1 row in set (0.017 sec)