Shulou(Shulou.com)06/01 Report--

QUESTION 1

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

Correct Answer: BC

Explanation/Reference:

Checkpoint process:

The checkpoint process (CKPT) updates the control file and data file headers with checkpoint information and signals DBWn to write blocks to disk. Checkpoint information includes the checkpoint position, SCN, location in online redo log to begin recovery, and so on. CKPT does not write data blocks to data files or redo blocks to online redo log files.

Checkpoint function:

(1)Regularly encourage DBWn processes to write dirty blocks of memory back to data files without losing data when the database fails

(2)Reduce instance recovery time

(3)Ensure that all committed data is written to the data file during consistency shutdown

Instance recovery time:

The time required to advance the last checkpoint (checkpoint location) of the data file to the latest SCN recorded in the control file. Administrators can control this time by setting MTTR targets and resizing redo log groups.

MTTR:

Mean Time To Repair, Mean Time to Repair. MTTR is the average time to repair of a repairable product, i.e. the time between failure and repair. You can control how long it takes for the database to perform crash recovery on a single instance by setting the FAST_START_MTTR_TARGET parameter in seconds.

FAST_START_MTTR_TARGE= non-zero value, enables fast start checkpoint function, automatically controls checkpoint speed.

FAST_START_MTTR_TARGE=0, disables the Fast Start Checkpoint feature.

If the size of the redo log file is too small, it will switch logs frequently, that is, checkpoints will occur frequently, so you can increase the size of the redo log file to reduce the frequency of checkpoints.

FAST_START_MTTR_TARGET If the setting is too small, checkpoints must occur frequently in order to control the recovery time of a single instance of the database to ensure that modified data blocks in memory can be written to disk regularly, so you can use MTTR Advisor to set the recommended value.

For more question bank analysis, please pay attention to: ke.qq.com/cgi-bin/courseDetail? course_id=36323

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.