|
Currently system versioning does not work at all even for simplest table types of CONNECT engine, e.g. DOS, I assume due to MDEV-15967 – microseconds are not stored, so the stored value of row end is less than expected, and all data is considered outdated.
MariaDB [test]> create or replace table t3 (a int) engine=CONNECT table_type=DOS file_name='t3.file' with system versioning;
|
Query OK, 0 rows affected (0.05 sec)
|
|
MariaDB [test]> insert into t3 values (1);
|
Query OK, 1 row affected (0.00 sec)
|
|
MariaDB [test]> select * from t3;
|
Empty set (0.01 sec)
|
|
MariaDB [test]> select *, row_start, row_end from t3 for system_time all;
|
+------+----------------------------+----------------------------+
|
| a | row_start | row_end |
|
+------+----------------------------+----------------------------+
|
| 1 | 2018-04-22 02:46:28.000000 | 2038-01-19 05:14:07.000000 |
|
+------+----------------------------+----------------------------+
|
1 row in set (0.00 sec)
|
So, unless MDEV-15967 is fixed by GA, versioning for CONNECT should be disabled.
However, I'm not sure it makes much sense to keep it even if MDEV-15967 gets fixed. Most CONNECT table types provide access to external data sources, and versioning will be either impossible at all, or its semantics will be questionable.
|