Hi Sergei, Please review a patch that merges a new read-only variables --explicit-defaults-for-timestamp from MySQL. Note, the original MySQL patch updates many tests, to make the tests independent from the compiled-in default --explicit-defaults-for-timestamp value. I guess Oracle is planning to change the default value to ON eventually. I merged these changes for tests as well. As a result, all tests pass in both "mtr" and "mtr --mysqld=--explicit-defaults-for-timestamp", which I think is good. In addition to the original MySQL changes in mtr, I also added two tests that describe specific behavior: sys_vars.explicit_defaults_for_timestamp_off sys_vars.explicit_defaults_for_timestamp_on Note, the patch assumes that the server and the slave have the same --explicit-defaults-for-timeatamp. Monty suggested to make this variable dynamic and replication-safe. We added a separate task for this: MDEV-8455 Make --explicit-defaults-for-timestamp dynamic I plan to do it in the next 10.1 sprint round. Thanks.