Oracle Oracle Database 1Z0-888 Questions & Answers

• Question 21:

  You have been tasked with creating a QA MySQL instance on a DB host, which already has one large instance in /var/lib/mysql/ running as the mysql user. The MySQL configuration file for the existing instance includes:

  

  The default instance was installed using the OS package manager. The latest binaries for both client and server are already in ENV PATH.

  The new instance will run as a different user from the existing instance for security purposes. You create the new data directory successfully and move on to initialize the new DATADIR.

  You verify the output to confirm the operation's success:

  [mysqlQA@linux /var/lib/]$ mysqld --initialize --datadir=/var/lib/mysql_QA 2>and1 | tail -n3

  2018-05-03T12:16:10.928809Z 0 [ERROR] Could not open file '/var/log/mysqld.log' for error logging:

  Permission denied

  2018-05-03T12:16:10.928841Z 0 [ERROR] Aborting

  [mysqlQA@linux /var/lib/]$

  The initialization of the instance has failed.

  What would you do to enable the initialization to succeed?

  A. Pass --log-error=/var/lib/mysql_QA/mysqld.log.

  B. Use mysql_install_db.

  C. Use --no-defaults to ignore the existing config file in the default PATH.

  D. Change permissions on /var/log/mysqld.log to allow writes.

  Correct Answer: B

  mysql_install_db handles initialization tasks that must be performed before the MySQL server, mysqld, is ready to use.

  Reference: https://dev.mysql.com/doc/refman/5.7/en/mysql-install-db.html

• Question 22:

  Which two statements can be used to adjust the sort_buffer_size variable on a running MySQL server? (Choose two.)

  A. mysql> SET GLOBAL sort_buffer_size=256000;

  B. mysql> SET SESSION sort_buffer_size=256000;

  C. mysql> CONF T; do global sort_buffer_size=256000;

  D. mysql> system sort_buffer_size=256000;

  E. mysql> SET VARIABLE sort_buffer_size=256000;

  Correct Answer: AB

  SET GLOBAL sort_buffer_size = 1000000, SESSION sort_buffer_size = 1000000; Reference:https://dev.mysql.com/doc/refman/5.7/en/set-variable.html

• Question 23:

  The MySQL instance is a default RPM installation on a Linux server. Where are the errors written?

  A. in the /var/lib/mysql/hostname.log file

  B. no logging enabled by default

  C. in the /var/log/mysqld.err file

  D. in the syslog daemon on the server

  Correct Answer: C

  are set to the file/var/log/mysql/error.log

  Reference: https://support.plesk.com/hc/en-us/articles/115004039393-Unable-to-start-mysql-var-logmysql-error-log-Permission-denied

• Question 24:

  You are looking at these details:

  

  Why does the message "Waiting for an event from Coordinator" show up on the slave_worker threads?

  A. The Event Schedular is not enabled on the slave host.

  B. The slave is waiting for an event to come into the relay log.

  C. The slave thread is waiting for another event to finish in another slave thread.

  D. The binary log on the master is not being updated.

  Correct Answer: A

  Reference: https://jira.mariadb.org/browse/MDEV-15426

• Question 25:

  What does the Performance Schema provide?

  A. insight into the internal working of MySQL

  B. recommendations for schema changes

  C. a text-based version of MySQL Enterprise Monitor

  D. auto-tuning based on settings and ongoing workload

  Correct Answer: A

  Reference: https://dev.mysql.com/doc/refman/8.0/en/performance-schema.html

• Question 26:

  Recently, users on mostly-write MySQL database have been complaining of slowdowns or stalls in their applications.

  Which option is most likely to have a positive effect on the server's health and performance?

  A. Reduce the size of redo logs to improve storage efficiency.

  B. Increase the size of redo logs.

  C. Lower innodb_max_dirty_pages_pct to flush more often.

  D. Move redo logs to /dev/shm to improve their speed.

  Correct Answer: C

  Reference:https://books.google.com.pk/books?id=QWOZBAAAQBAJandpg=PT179andlpg=PT179anddq=Lower +innodb_max_dirty_pages_pct+to+flush+more+often.andsource=blandots=FwmB-8zI9Mandsig=ACfU3U0zLNCENrOcvMfEALc4pPxiOj81Qandhl=enandsa=Xandved=2ahUKEwiGk4iv0KnpAhWjzYUKHS54CK0Q6AEwAHoECAoQAQ#v=onepageandq =mysqlandf=false

• Question 27:

  Consider a replication setup where a snapshot of the replication status shows: Which statement is true?

  

  A. The melbourne channel is resolving a GTID conflict.

  B. The sydney channel is keeping up with the received events.

  C. The melbourne channel is keeping up with the received events.

  D. The last event received from the sydney channel was at 2018-05-08 14:55:01.

  E. The replication slave uses multisource replication with eight sources.

  Correct Answer: E

• Question 28:

  What three are correct statements about MySQL backups? (Choose three.)

  A. They are used to set up the initial binary log files.

  B. They are used to prevent data corruption.

  C. They are used to prevent data theft.

  D. They are used to set up a replication slave.

  E. They are used to recover data.

  F. They are used to set up a test system.

  Correct Answer: ADE

  Reference: https://dev.mysql.com/doc/mysql-backup-excerpt/5.6/en/point-in-time-recovery.html https://www.digitalocean.com/community/tutorials/how-to-set-up-master-slave-replication-in-mysql https://hetmanrecovery.com/recovery_news/restoring-deleted-mysql-database-files.htm

• Question 29:

  You have set innodb_stats_auto_recalc to OFF.

  For tables using persistent statistics, what is the outcome of this change?

  A. InnoDB no longer automatically updates index statistics after a CREATE TABLE statement.

  B. InnoDB no longer automatically updates index statistics after the table structure is altered.

  C. InnoDB no longer automatically updates index statistics after 10% of the rows in a table change.

  D. InnoDB no longer automatically updates index statistics after an ANALYZE TABLE statement.

  Correct Answer: C

  Reference: https://dev.mysql.com/doc/refman/5.7/en/innodb-parameters.html

• Question 30:

  To query two system variables, you execute this statement and get the results shown:

  

  When you execute the following two statements, only the first one succeeds:

  SET @@autocommit=0;

  SET @@max_connections=200;

  Why does the second statement fail?

  A. max_connections is a read-only variable that cannot be set dynamically.

  B. max_connections must be set globally instead of locally.

  C. max_connections is a derived variable that can only be set indirectly.

  D. max_connections must be set at server start in an options file.

  Correct Answer: D

  Reference: https://books.google.com.pk/books?id=N4KzO2Tih98Candpg=PA385andlpg=PA385anddq=max_connections +must+be+set+at+server+start+in+an+options +file.andsource=blandots=KvEbu8PbDOandsig=ACfU3U1v48_bQW7O0JIjzTJ6NmL6bVsfwandhl=enandsa=Xandved=2ahUKEwj5x9iU5KfpAhXX3YUKHUlQCd8Q6AEwA3oECAgQAQ#v=onepage andq=max_connections%20must%20be%20set%20at%20server%20start%20in%20an%20options% 20file.andf=false