yes - the another little bit unclean in EXPLAIN is number of workers. If I understand to the behave, the query is processed by two processes if workers in the explain is one.
You are right and I think that is current working model of Gather
node which seems okay. I think the more serious thing here
is that there is possibility that Explain Analyze can show the
number of workers as more than actual workers working for Gather
node. We have already discussed that Explain Analyze should
the actual number of workers used in query execution, patch for
