VSCopy: Copy from all shards in all keyspaces by specifying only an empty gtid

[yoheimuta]

Feature Description

If either keyspace or shard is unspecified, the request with an empty gtid like the following should copy tables from all shards in all keyspaces.

vgtid := &binlogdatapb.VGtid{
         		ShardGtids: []*binlogdatapb.ShardGtid{{
         			Gtid:     "",
                }}
         }

Currently, this request fails due to INVALID_ARGUMENT at the below two checks:

• vitess/go/vt/vtgate/vstream_manager.go

  Lines 186 to 188 in a36de2c

  	if vgtid.ShardGtids[0].Gtid != "current" {
  	return nil, nil, nil, vterrors.Errorf(vtrpcpb.Code_INVALID_ARGUMENT, "for an empty keyspace, the Gtid value must be 'current': %v", vgtid)
  	}

• vitess/go/vt/vtgate/vstream_manager.go

  Lines 205 to 207 in a36de2c

  	if sgtid.Gtid != "current" {
  	return nil, nil, nil, vterrors.Errorf(vtrpcpb.Code_INVALID_ARGUMENT, "if shards are unspecified, the Gtid value must be 'current': %v", vgtid)
  	}

Discussion

https://vitess.slack.com/archives/C0PQY0PTK/p1670315632556969

Use Case(s)

• Copying tables across many shards and keyspaces through VTGate's VStream API