mysql8.0英文OCP考试第11-20题

Q11.Examine this command and output:

Mysql>SELECT *

        FROM performance_schema.table_10_waits_summary_by_table

       WHERE COUNT_STAAR >0\G

********************************2.row **************************************

        OBJECT_TYPE:TABLE

OBJECT_SCHEMA:test

OBJECT_NAME:demo_test

CONUNT_STAR:61567093

SUM_TIMER_WAIT:59009007572922

MIN_TIMER_WAIT:395922

AVG_TIMER_WAIT:958095

MAX_TIMER_WAIT:558852005358

COUNT_READ:38665056

SUM_TIMER_READ:20598719962188

MIN_TIMER_READ:395922

AVG_TIMER_READ:532728

MAX_TIMER_READ:558852005358

COUNT_WRITE:22902028

SUM_TIMER_WRITE:38410287610743

MIN_TIMER_WRITE:1130688

AVG_TIMER_WRITE:1677006

MAX_TIMER_WRITE:17205682920

    COUNT_FETCH:38665056

SUM_TIMER_FETCH:20598719962188

MIN_TIMER_FETCH:395922

AVG_TIMER_FETCH:532728

MAX_TIMER_FETCH:558852005358

 .....

 COUNT_DELETE:22902028

SUM_TIMER_DELETE:38410287610743

MIN_TIMER_DELETE:1130688

AVG_TIMER_DELETE:1677006

MAX_TIMER_DELETE:17205682920

Which two are true?

A)The longest I/O wait was for writes.

B)I/O distribution is approximately 50/50 read/write.

C)22902028 rows were deleted.  

D)Average read times are approximately three times faster than writes.

E)The I/O average time is 532728.

Answer:CD

Q12.A developer accidentally dropped the InnoDB table Customers from the Company database. There is a datadir copy from two days ago in the dbbackup directory.

Which set of steps would restore only the missing table?

A)Stop the MySQL Server process, and execute: