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Re: 答复: 答复: 答复: MDEV-520: consider parallel replication patch from taobao patches



>>>>> "Kristian" == Kristian Nielsen <knielsen@xxxxxxxxxxxxxxx> writes:

Kristian> Stewart Smith <stewart@xxxxxxxxxxxxxxxx> writes:
>> What about just run those txns serially rather than attempting to do in
>> parallel?

Kristian> Maybe. Well, first we need to generalise "MyISAM" and "InnoDB" to a general
Kristian> way of putting any storage engine into one or the other category. I assume
Kristian> Monty or Serg can help me figure out how to do this.

>> As soon as you see a MyISAM operation, have a thread that waits for all
>> replication up to that point to be committed, and then do the MyISAM
>> operation. (as there's no reason why other replication couldn't be
>> applied at the same time... after all, MyISAM isn't crash safe so would
>> never be consistent with InnoDB txns).


Kristian> MyISAM is not MVCC nor does it have COMMIT, so it seems by default we should
Kristian> do what you suggest: run MyISAM transactions serially. In fact they have to
Kristian> run serially with respect to InnoDB transactions also, to avoid getting the
Kristian> slave into a state that might be invalid to the application.

Note that MyISAM can mix SELECT and INSERT and these behave as there
would be MVCC.