can't start a GTID-based incremental task when upstream GTID is empty

[lance6716]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. What did you do? If possible, provide a recipe for reproducing the error.

upstream gtid is empty, and binlog-gtid in meta field in task file is also empty

2. What did you expect to see?

start successfully

3. What did you see instead?

query-status shows "invalid position (mysql-bin.000001, 4) or GTID not enabled in upstream"

4. Versions of the cluster

   • DM version (run dmctl -V or dm-worker -V or dm-master -V):

     v2.0.5
     

[lance6716]

it's very annoying because many of out internal logic can't tell empty GTID set from GTID not enabled. Like

tiflow/dm/syncer/syncer.go

Line 3695 in cdc9fa5

if !s.cfg.EnableGTID || location.GTIDSetStr() != "" || location.Position.Name == "" {

/cc @niubell

[niubell]

/assign D3Hunter

[lance6716]

During a little refactor, I think we can use nil gtid to represent "gtid not enabled", and empty string to represent empty gtid. Do you have some suggrestions @D3Hunter

[D3Hunter]

so hacky, why not check s.cfg.EnableGTID directly

[niubell]

/assign gmhdbjd

[niubell]

/unassign D3Hunter