“U” entries in MLOG$

Recently in a discussion with colleague, on what entries do MLOG$ have, the following was agreed to :- 1. "I" for insert 2. "D" for delete 3. "D" + "I" for update. Along with the above entries, you might notice "U" also. The "U" entry is for update. But then, on what condition do we … Continue reading “U” entries in MLOG$


Enabling Flashback – Be Cautious

Enabling flashback on database can take minutes and cause multiple database wait events degrading database performance. On a quite busy system, during the low peak hours, I tried to enable flashback on version database and multiple sessions waited on 1. buffer exterminate 2. enq: SQ - contention 3. latch: cbc contention 4. SGA: … Continue reading Enabling Flashback – Be Cautious