VReplication: How does onlineddl.Executor interacts with VReplication?

[earayu]

1. What's the API
2. Does onlineddl.Executor call RPCs? or write data into a system table? ...

[earayu]

API:

• terminateVReplMigration(ctx, onlineDDL.Schema, onlineDDL.UUID)
• initVreplicationOriginalMigration(ctx, onlineDDL, conn)
• initVreplicationRevertMigration(ctx, onlineDDL, revertMigration)
• VRepl.analyze(ctx, conn)
• updateMigrationTableRows(ctx, onlineDDL.UUID, v.tableRows)
• postInitVreplicationOriginalMigration(ctx, onlineDDL, v, conn)
• vreplicationExec(ctx, tablet.Tablet, insertVReplicationQuery)

[earayu]

onlineddl.Executor interacts with VReplication by INSERT/UPDATE/DELETE vreplication system table:

1. onlineddl.Executor need to call tabletManager via gRPC
2. tabletManager will call vreplication.Engine
3. vreplication.Engine will finally execute the query passed from step 1
4. vreplication.Engine will also control the VReplication Job

[earayu]

• onlineddl.Executor#vreplicationExec
  • tabletManager#VReplicationExec
    • vreplication.Engine#ExecWithDBA