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 derived variable that can only be set indirectly.
• B. max_connections must be set at server start in an options file.
• C. max_connections must be set globally instead of locally.
• D. max_connections is a read-only variable that cannot be set dynamically.

Examine the mysqldumpslow output:

Which two options could explain the slow query?

• A. No index has been defined on the filtered column.
• B. There is network congestion between client and server.
• C. A table lock is causing delays.
• D. There are 108 queries still being executed.
• E. A full table scan is being used.

You have issued this statement:
GRANT PROXY ON 'a' FOR 'b';
When user account 'b' issues a query, the query returns an access denied error.
What could have caused that error?

• A. User account 'a' has not been granted permission to access the data being queried.
• B. User account 'b' has not been granted permission to access the data being queried.
• C. When connecting, user account 'b' is not entering the correct password for user account 'a'.
• D. You have not set the proxy_user variable in the configuration file.

Which statement best describes the purpose of the InnoDB buffer pool?

• A. It caches only the indexes for InnoDB tables.
• B. It holds changes made during a transaction before they are written to the log.
• C. It is a pool of memory for SQL query sort operations from within the InnoDB engine.
• D. It caches data and indexes for InnoDB tables.
• E. It is amount of buffers available during a transaction.