Since ON CONFLICT does not work with partitions, I have designed an aggregation appender by hand using UPDATE (for existed rows) + INSERT (for new ones). Unexpectedly I got a strange result as a count of updated (really joined) rows running that function cuncurrently on 9.5.5 and 9.5.7 (9.5.2 works correctly). The got value exceeds the expected result by 1
Can you run this against 9.5.10 and see if it is still a problem? Its seems the last couple of bug fix patches covered something that sounds familiar.