A.— quickB.— skip-bufferC.— single-transactionD.— tabYo……

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

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

单项选择题An employee cannot access the company database. You check the connection variables: What is a valid explanation for why one of the users is unable to connect to the database?（）

A.Bob has max_user_connections set to zero, which blocks all his connections
B.Joe has exceeded the max_user_connections global limit
C.All users are blocked because max_user_connections is accumulated over the host account information
D.Kay is already connected elsewhere and attempting to log in again
E.Connect_timeout is too small to allow a connection to occur

单项选择题Your developers have created table to store some of their programs data. After examining the slow Query Log, you see that they are using the LIKE operator and SUBSTER () functions against a VARCHAR (10000) column quite often. An example of the start of one row of data: GREEN01020495888331993-12-10 2… What should you do to improve the overall performance?（）

A.Convert the column to TEXT and add a fulltext index to the table
B.Create multiple prefix indexes of differing lengths
C.Convert their column to BINARY
D.Redesign the table so that the most commonly searched for string patterns are in their own columns