You notice that the performance of the database has degraded because of frequent checkpoints.
Which two actions resolve the issue? (Choose two.)
A.
Disable automatic checkpoint tuning
B.
Check the size of the redo log file size and increase the size if it is small
C.
Set the FAST_START_MTTR_TARGET parameter as per the advice given by the MTTR Advisor
D.
Decrease the number of redo log members if there are more than one redo log members available in each redo log group
Why if oracle said that no more checkpoints ocurr after a swith log file?
Oracle document said that: when log switch occurs, check point will be activated!
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CHECKPOINT:data blocks from buffer cache are written to the data files.
Data file headers and controlfile headers are also updated with the latest checkpoint SCN, even if the file had no changed blocks.
or
CHECKPOINT is highest system change number (SCN) such that all data blocks less than or equal to that SCN are known to be written out to the data files.
Checkpoint occurs when,
1.Log switch occurs
2. at intervals specified by initialization parameters.
The duration of cache recovery processing is determined by two factors: the number of data blocks that have changes at SCNs higher than the SCN of the checkpoint, and the number of log blocks that need to be read to find those changes
If a failure occurs, then only the redo records (containing changes) at SCNs higher than the checkpoint need to be applied during recovery
Frequent checkpoint REDUCES CHACHE REDCOVERY TIME in the event of an instance failure
However can REDUCE RUNTIME PERFORMANCE, because checkpointing causes DBWn processes to perform writes.
—>So if the log size is increase then log switch will happen less frequently unless it is manually switched.Hence the checkpointing will occur less.
—> (MTTR), which is the expected amount of time Oracle takes to perform recovery and startup the instance
Oracle continuously estimates the recovery time and automatically adjusts the check-pointing rate to meet the target recovery time.
MTTR is for automatic checkpointing,if we disable this parameter to 0,oracle will adjust parameter to not perform checkpoints automatically.