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The InnoDB engine has a feature known as clustered indexes.
Which three statements are true about clustered indexes as used in InnoDB?（）

A.A primary key must exist for creation of a clustered index
B.A clustered index allows fulltext searching within InnoDB
C.The first unique index is always used as a clustered index and not a primary key
D.A clustered index provides direct access to a page containing row data
E.If no indexes exist, a hidden clustered index is generated based on row IDs
F.A primary key is used as a clustered index
G.A clustered index is a grouping of indexes from different tables into a global index for faster searching

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多项选择题Which two events will cause a slave server to create a new relay log file?（）

A.Execution of the FLUSH LOGS statement
B.Starting of the SQL thread
C.Reaching the slave_pendign _jobs_size_max limit
D.Execution of FULSH TABLES WITH READ LOCK
E.Starting of the I/O thread

单项选择题You want to start monitoring statistics on the distribution of storage engines that are being used and the average sizes of tables in the various databases. Some details are as follows: The Mysql instance has 400 databases. Each database on an average consists of 25-50 tables. You use the query: SELECT TABLE_SCHEMA, ENGINE, COUNT (*), SUM(data_length) total_size FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_TYPE= BASE TABLE GROUP BY TABLE_SCHEMA, ENGINE ; Why is this query slow to execute?（）

A.Collecting information requires large numbers of locks on various INFORMATION_SCHEMA tables
B.Aggregating details from various storage engine caches for the final output is time consuming
C.Collecting information requires various disk-level operations and is time consuming
D.Counting and summarizing all table pages in the InnoDB shared tablespace is time consuming

多项选择题Which two are correct steps in taking a binary backup of MyISAM tables?（）

A.Always stop the server prior to the backup
B.Stop the server or lock the tables prior to the backup
C.Stop the server or lock the databases prior to the backup
D.Make a copy of the .frm, .myd, and the .myi files
E.Make a copy of the binary log and tablespace files

单项选择题Which statement is true about FLUSH LOGS command?（）

A.It requires the RELOAD, FILE, and DROP privileges
B.It closes and reopens all log files
C.It closes and sends binary log files to slave servers
D.It flushes dirty pages in the buffer pool to the REDO logs

单项选择题Identify a performance impact when using the Performance Schema.（）

A.There is no impact on performance
B.The overhead depends on the settings of the Performance Schema
C.There is an overhead for querying the Performance Schema but not for having it enabled
D.There is a constant overhead regardless of settings and workload