Query featuring outer joins behaves differently in Oracle 12c

Question

I had a problem come through concerning missing data on Oracle 12c.

I took a look at the code and found a query that works on mysql, mssql, oracle 11g, but has diffe

Answer 1

I've a migration planned from 11gR2 to 12c and whole lot of syntax is in ANSI. Its really a nightmare to test each and every query and compare it with the 11g data. Is setting alter session set "_optimizer_ansi_rearchitecture"=false; is the only solution or the bug is fixed