多项选择题

Which three tasks can be performed by using the performance Schema?（）

A.Finding queries that are not using indexes
B.Finding rows that are locked by InnoDB
C.Finding client connection attributes
D.Finding the part of a code in which a single query is spending time
E.Finding the size of each table

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热门试题

多项选择题

Which three statements are true about memory buffer allocation by a MySQL Server?（）

A.Global buffers such as the InnoDB buffer pool are allocated after the server starts, and are never freed
B.Thread buffers are allocated when a client connects, and are freed when the client disconnects
C.Buffers that are needed for certain operation are allocated when the operation starts, and freed when it ends
D.User buffers are allocated at server startup and freed when the user is dropped
E.All dynamic buffers that are set with a SET GLOBAL statement immediately get allocated globally, and are never freed

单项选择题

Consider the following: Which statement best describes the meaning of the value for the key_len column?（）

A.It shows the total size of the index row
B.It shows how many columns in the index are examined
C.It shows the number of characters indexed in the key
D.It shows how many bytes will be used from each index row