You are administering a database that supports an OLTP workload. An application performs
a large number of small transactions. Users complain about increased response times for
transactions. On investigation, you find that the cache hit ratiois 69%. Examine a partial
output from V$SYSTEM_EVENT:
Which four can be possible reasons for the increased response time?(Choose four.)
A.
The database buffer cache is inadequately sized.
B.
DBWR is not writing the dirty buffers fast enough.
C.
A large number of blocks are fetched from disks frequently.
D.
Several full table scans are performed by transactions.
E.
Blocks are aging out of the buffer cache frequently.
F.
Many sessions are waiting for buffers that are currently being read into the buffer cache
by other sessions.
B – free buffer waits,
E – low cache hit ration
F – read by other session
and
D – several full table scans are performed by transactions
BCEF
BCEF
I doubt because the Oracle documentation says the following:
https://docs.oracle.com/database/121/TGDBA/tune_buffer_cache.htm#TGDBA537
Do not continuously increase the buffer cache size.
Continuous increases of the buffer cache size have no effect if the database is performing full table scans or operations that do not use the buffer cache.
Mb A,B,C,F
A,B,E,F
C is wrong. I think it says about the hot blocks, it is difficult to say how many of them
D is wrong. read by other session, and buffer busy waits events occur not only on full table scans
ABEF yep, others are not “prooved”