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pt-online-schema-change: idea for improvement / change to let it work with triggers

Ronny GörnerRonny Görner Current User Role Supporter
Changing a scheme on altering a table with an existing trigger results in an error because (cluster on Enforcing mode), it uses lock tables to switch the trigger, and lock tables are of course not supported to work with xtradb cluster or any other galera powered multi-master-replication.
On code line 11291 and forward, there is use of the Lock command let the commandset not work.
In my eyes, we would need to have 2 new options on the commandline to let it work:
--xtradb-cluster (to enable the script for xtradb cluster)
--xtradb-timeout (for example 30 s as a default value, will interupt wait for lock if overclocked that database is not blocked at all for longer time)
What I want to achieve:
Enabling and integrating those 2 new options, altering a table having existing triggers will work until the trigger is migrated. Lock tables is not working, but "flush table with read lock" maybe would. So, if the option is set, just use this command, this command maybe can work. But am not sure, documentation is confusing me, on the on hand, the Lock/Unlock and flush is not supported, on the other hand, percona xtradb seems to use it or handles it that way.


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