This is real results from my database. I spend some time trying to reproduce this behavior with an SSCCE but failed. How is the last of the below results possible?
SELECT COUNT(*) FROM rr.resource a --- 15771 SELECT COUNT(*) FROM rr.resource a NATURAL JOIN rr.interface b --- 41419 SELECT COUNT(*) FROM rr.resource a NATURAL JOIN rr.interface b NATURAL JOIN rr.interface c --- 0
The zero (0) row count in the last query is consistent and repeatable every time. In some examples I created, adding a second natural join with the same table twice yields the same number of rows (as I was expecting). How is then the above result possible?