MyRocks does commit step non-durably under server group 2PC protocol about mysql-5.6

[laurynas-biveinis]

It looks like this behavior is an undocumented deliberate design decision.The server layer requests commits to be non-durable too in addition to prepares, when binlog is enabled. InnoDB does the same thing: https://bugs.mysql.com/bug.php?id=75519

Since InnoDB is the DDSE, it also unconditionally flushes the redo log on any DD operation. This way it addresses the scenario above where it recovers individually from the redo log, initializes the data dictionary, and only then binlog crash recovery runs. It looks like MyRocks DDSE will have to flush on every DD operation commit too.

I will still make a PR but only to check the server durability request individually at commit time too, instead of assuming that prepare and commit requested the same.

Any other changes we'd make eventually will depend on the resolution of https://bugs.mysql.com/bug.php?id=75519, if any