Migrate OnlineDDL commands to vtctldclient

[ajm188]

• Define protobuf message for OnlineDDL messages #13713
• Migrate OnlineDDL Show #13714
• Migrate OnlineDDL Cleanup #13715
• Migrate OnlineDDL Retry #13716
• Migrate OnlineDDL Cancel #13717
• Migrate OnlineDDL Launch #13718
• Migrate OnlineDDL Complete #13719
• Migrate OnlineDDL Throttle #13720
• Migrate OnlineDDL Unthrottle #13721

[shlomi-noach]

I'm having second thoughts about throttle and unthrottler. Following v17 changes, these commands should not make it to the tabletmanager at all. In fact, if you issue alter vitess_migration throttle all command in vtgate, your query gets handled differently than an alter vitess_migration complete all: vtgate will run specialized code to UpdateSrvKeyspace in the throttle case, where for complete it will just send the query to the tablet.

I'd rather cut hard at this time and simply not implement throttle and unthrottle. What was originally conceived as consistent queries/behavior is now very different, and today I would now add these commands in vtctl nor in vtgate.

[shlomi-noach]

@ajm188 what are your thoughts?

[ajm188]

vtgate will run specialized code to UpdateSrvKeyspace in the throttle case, where for complete it will just send the query to the tablet.

I'd rather cut hard at this time and simply not implement throttle and unthrottle. What was originally conceived as consistent queries/behavior is now very different, and today I would now add these commands in vtctl nor in vtgate.

So, is the "right" way now to call UpdateSrvKeyspace with vtctdlclient? Or to call UpdateThrottlerConfig? I don't see why the vtctld rpc can't be a wrapper to pass specific values to those same functions (i.e. vtctldclient Throttle <uuid> is equivalent to vtctldclient UpdateThrottlerConfig <payload relating to the specific schema migration with "uuid">)