I would think that adding system versioning for (some) system tables is a reasonable idea, given that they are not updated so often, but are extremely important. However, it doesn't work (in different ways), a couple examples are below; there are probably more, I didn't try other tables yet. Not sure whether it should be fixed or prohibited, but either one or another should be done.
alter table mysql.user add system versioning;
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# Query OK, 2 rows affected (0.04 sec)
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select user, host, sys_trx_start, sys_trx_end from mysql.user for system_time all;
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# +------+-----------+----------------------------+----------------------------+
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# | user | host | sys_trx_start | sys_trx_end |
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# +------+-----------+----------------------------+----------------------------+
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# | root | localhost | 2017-12-28 19:40:13.453770 | 2038-01-19 05:14:07.999999 |
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# | root | 127.0.0.1 | 2017-12-28 19:40:13.453770 | 2038-01-19 05:14:07.999999 |
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# +------+-----------+----------------------------+----------------------------+
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create user foo@localhost;
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# Query OK, 0 rows affected (0.00 sec)
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select user, host, sys_trx_start, sys_trx_end from mysql.user for system_time as of current_timestamp;
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# +------+-----------+----------------------------+----------------------------+
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# | user | host | sys_trx_start | sys_trx_end |
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# +------+-----------+----------------------------+----------------------------+
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# | root | localhost | 2017-12-28 19:40:13.453770 | 2038-01-19 05:14:07.999999 |
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# | root | 127.0.0.1 | 2017-12-28 19:40:13.453770 | 2038-01-19 05:14:07.999999 |
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# +------+-----------+----------------------------+----------------------------+
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select user, host, sys_trx_start, sys_trx_end from mysql.user for system_time all;
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# +------+-----------+----------------------------+----------------------------+
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# | user | host | sys_trx_start | sys_trx_end |
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# +------+-----------+----------------------------+----------------------------+
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# | root | localhost | 2017-12-28 19:40:13.453770 | 2038-01-19 05:14:07.999999 |
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# | root | 127.0.0.1 | 2017-12-28 19:40:13.453770 | 2038-01-19 05:14:07.999999 |
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# | foo | localhost | NULL | 0000-00-00 00:00:00.000000 |
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# +------+-----------+----------------------------+----------------------------+
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alter table mysql.proc add system versioning;
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# Query OK, 2 rows affected (0.04 sec)
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create procedure pr() begin end;
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# ERROR 1805 (HY000): Column count of mysql.proc is wrong. Expected 21, found 23. The table is probably corrupted
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Bug
Critical
