make `start-relay` easier to use

lance6716 commented 3 years ago

Is your feature request related to a problem? Please describe

I want to start relay to reduce the number of upstream binlog replication slaves, not care about which worker started relay so don't want to specify worker name. Currently I must specify worker name of the source is bound or free
~I want to specify the position from which the relay is pulling. Currently this is specified in source configuration file, which is hard to modify~

Describe the feature you'd like

start-relay -s <source-id>, stop-relay -s <source-id> to let current and future bound workers use relay to replicate. and this feature is exclusive from start-relay -s <source-id> <worker-names>, which means

start-relay -s source1         # now DM will start relay for current and future bound workers
start-relay -s source1 worker2 # DM will raise error: "this source has automatically started relay for bound worker, can't specify worker using relay now"
stop-relay -s source1 worker1  # DM will raise error: "this source has automatically started relay for bound worker, can't specify worker stopping relay now"
stop-relay -s source1          # now DM will stop relay for current and future bound workers
start-relay -s source1 worker2 # DM will let worker2 pull relay log of source1
start-relay -s source1         # DM will raise error: "this source has started relay for specified worker [worker1], can't automatically started relay for bound worker now"
stop-relay -s source1          # DM will raise error: "this source has started relay for specified worker [worker1], can't automatically stop relay for bound worker now"
stop-relay -s source1 worker2  # success

~start-relay -s <source-id> <worker-name> --binlog-file <filename> --binlog-pos <position> or start-relay -s <source-id> <worker-name> --binlog-gtid <gtid set>~

Describe alternatives you've considered

No response

Teachability, Documentation, Adoption, Migration Strategy

No response

lance6716 commented 3 years ago

PTAL @sunzhaoyang

lance6716 commented 3 years ago

and for https://github.com/pingcap/dm/issues/2205, I'm requesting

start-relay --all --on-bound, stop-relay --all --on-bound

lichunzhu commented 3 years ago

I prefer start-relay -s <source-name> [worker-name]. If worker-name is not specified, start-relay for all source-name bound workers.

Ehco1996 commented 3 years ago

I prefer start-relay -s <source-name> [worker-name]. If worker-name is not specified, start-relay for all source-name bound workers.

what is "for all source-name bound workers" ？ does this mean that all worker that have bound this source?

lance6716 commented 3 years ago

updated the issue description

pingcap / dm