We have had a performance problem on a particular APEX screen, ever since we had to perform a Dataguard failover 10 days ago. I'd put it down to general system load until I investigated more deeply today. The Underlying SQL runs fine, running as the same user, via SQL (<0.1 seconds). Via the application, using the same bind variables it takes > 70s. What is really confusing me is the dbms_xplan output is stating
- rule based optimizer used (consider using cbo)
in the report. I didn't think that was even possible any more? I'll raise an SR if needed, but before I go down that rabbit hole, has anyone seen this before? Any idea where to look? We did manage to lose a couple of parameters on the failover, I thought I'd found them all but maybe not? It's not a global problem though, most things are working fine. Application hasn't changed in ages according to the DEV team.
Any suggestions, gratefully received!