RE: Perform streaming logical transactions by background workers and parallel apply

Dear Hou,

> while reading the code, I noticed that in pa_send_data() we set wait event
> to WAIT_EVENT_LOGICAL_PARALLEL_APPLY_STATE_CHANGE while sending
> the
> message to the queue. Because this state is used in multiple places, user might
> not be able to distinguish what they are waiting for. So It seems we'd better
> to use WAIT_EVENT_MQ_SEND here which will be eaier to distinguish and
> understand. Here is a tiny patch for that.

In LogicalParallelApplyLoop(), we introduced the new wait event
WAIT_EVENT_LOGICAL_PARALLEL_APPLY_MAIN whereas it is practically waits a shared
message queue and it seems to be same as WAIT_EVENT_MQ_RECEIVE.
Do you have a policy to reuse the event instead of adding a new event?

Best Regards,
Hayato Kuroda
FUJITSU LIMITED