Q1. Examine this command, which executes successfully:
mysqlbackup --user=dba --password --port=3306 --with-timestamp --backup-dir=/export/backups backup-and-apply-log
Which statement is true?
A)The backup accesses the MySQL server files by using a pre-existing connection.
B)The database server is put into a read-only state for the duration of the backup.
C)An offline backup of InnoDB tables is taken.
D)The backup can be impacted when DDL operations run during the backup.
详解：
参见《MySQL8.0 for Database Administrators studentGuide 2》243页
While the non-InnoDB backup runs:
--- Prior to version 8.0.16, the database cannot be modified
--- As of version 8.0.16, only non-InnoDB tables cannot be modified and InnoDB tables allow DML operations but not DDL operations
Answer:D
Q2.You reconfigure and start a slave that was not replicating for several days.
The configuration file and CHANGE MASTER command are correct. Examine the GTID information from both master and slave:
Master:
Gtids_executed: aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa:1-321,
bbbbbbbb-bbbb-bbbb-bbbbbbbbbbbb:1-50,
Cccccccc-cccc-cccc-cccc-cccccccccccc:1234-1237
Gtids_purged: aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa:1-100,
bbbbbbbb-bbbb-bbbb-bbbbbbbbbbbb:1-10,
cccccccc-cccc-cccc-cccc-cccccccccccc:1234-1237
Slave:
Gtids_executed: aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa:1-160,
cccccccc-cccc-cccc-cccc-cccccccccccc:1234-1237
Gtids_purged: aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa:1-70,
cccccccc-cccc-cccc-cccc-cccccccccccc:1234-1237
Which statement is true?
A)Replication will fail because the master does not have the required transaction with bbbbbbbb-bbbb-bbbb-bbbb-bbbbbbbbbbbb GTIDs in its binary logs.
B)Replication will fail because the master has already purged transactions with cccccccc-cccc-cccc-cccc-cccccccccc GTIDs.
C)Replication will fail because of inconsistent numbers in cccccccc-cccc-cccc-cccc-cccccccccccc GTIDs.
D)Replication will fail because the slave has purged more aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa transactions than the master.
F)Replication will work.
Answer:A