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

LGTM. My only comment is about the commit message.

======
Commit message

d9d7fe6 reuse existing wait event when sending data in apply worker. But we
should have invent a new wait state if we are waiting at a new place, so fix
this.

~

SUGGESTION
d9d7fe6 made use of an existing wait event when sending data from the apply
worker, but we should have invented a new wait state since the code was
waiting at a new place.

This patch corrects the mistake by using a new wait state
"LogicalApplySendData".

------
Kind Regards,
Peter Smith.
Fujitsu Australia