Tracking Issue: Replace VReplicationExec Command + RPC

[mattlord]

Feature Description

Replace the SQL based VReplicationExec API with 1+ properly encapsulated RPCs to meet any remaining use cases.

Details

vtctld makes fairly heavy use of the VReplicationExec RPC. This client-server interface (vtctld->vttablet) needs to be replaced because it does not do proper encapsulation and instead exposes the raw SQL interface. This causes problems for upgrades/downgrades where the internal schema changes as e.g. shown in #11535. As you can see from that bug report this RPC is used internally by, among other things, the implementation of the Workflow client command.

Using the Workflow command as an example, vtctld should instead leverage a new tabletmanager RPC, something like WorkflowAction where it passes the keyspace.workflow value, the action, and optional parameters such as the tablet-types or cells values for the update action (this still needs to be spec'd out). All other internal uses of the VReplicationExec RPC (primarily by vtctld via the wrangler component) would also be replaced.

Similarly, all other internal uses of the VReplicationExec RPC should be replaced by 1+ new purpose-built RPCs that support the use case with proper encapsulation.

The end result being that the raw SQL client-server interface for executing VReplication commands will be gone and replaced by 1 or more new RPCs with proper encapsulation.

Work

• Mark VReplicationExec Client Command as Deprecated #12070
• Replace VReplicationExec RPC usage (can be broken down by component if needed)
  • Remove Usage of VReplicationExec For _vt.vreplication Reads #14424
  • Replace remaining vtctldclient VReplicationExec RPC usage for the _vt.vreplication table #15439
  • Replace vtctldclient usage of VReplicationExec for the _vt.copy_state table #15441
  • Replace vtctldclient VReplicationExec usage for the _vt.vreplication_log table #15442
• Add any new client commands needed to obviateVReplicationExec client command: Add Workflow Update Client Command #12622
• Remove VReplicationExec client command

Related Issues

• Fixes: Compatibility issues between v11 and v12 for getting workflows #11535
• Fixes: Bug Report: SwitchTraffic in v15 not backwards compatible with v14 tablets #12100