单项选择题

What is true regarding InnoDB locking?（）

A.InnoDB uses row and table-level locks, but row locks are not escalates
B.InnoDB locks only those rows that are updated
C.InnoDB only uses row locks, not page or table-level locks
D.InnoDB row locks may be escalated to page or table-level locks
E.InnoDB uses row-level or table-level locks depending on the number of rows affected

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热门试题

单项选择题Which statement is true about the log-output variable?（）

A.It is a static variable and can be set only at MySQL server startup
B.It enables and starts the General Query Log
C.It sets the target location for the binary logs generated by the MySQL sever
D.It specifies output destinations for the slow and General Query logs

单项选择题You are investigating the performance of the server and see the following information: Events_waits_summary_global_by_event_name in the performance schema shows that the wait synch mutex sql LOCK_table_cache event is dominating other wait events. The table_open_cache_overflows status variable is 0. Which action should be taken to remove the performance bottleneck described here?（）

A.Increase the value of table_definition_cache
B.Increase the value of table_open_cache_instances
C.Decrease the value of table_open_cache_instances
D.Increase the value of table_open_cache
E.Decrease the value of table_definition_cache
F.Decrease the value of table_open_cache

多项选择题Which two statements are true about setting the per-thread buffers higher than required?（）

A.More memory per thread is beneficial in all scenarios
B.It causes increased overhead due to initial memory allocation
C.It can affect system stability during peak load times, due to swapping
D.It requires increasing the thread_cache_size variable

多项选择题In a test database, you issue the SELECT … INTO OUTFILE statement to create a file with your t1 table data. You then TRUNCATE this table to empty it.（） Mysql＞ SELECT * INTO OUTFILE tmp t1.sql from t1; mysql＞ TRUNCATE t1;

A.$ mysqladmin – u root – p – h localhost test – restore /tmp/t1.sql
B.Mysql＞ INSERT INTO t1 VALUES FROM '/tmp/t1.sql'
C.$ mysql – u root – p – h localhost test ＜ /tmp/t1.sql
D.Mysql＞ LOAD DATA INFILE '/tmp/t1.sql' INTO TABLE t1
E.$ mysqlinport – u root – p – h localhost test /tmp/t1.sql

多项选择题What are three facts about backups with mysqldump?（）

A.Can back up a remote database server
B.Allow a consistent backup to be taken
C.Are always faster to restore than binary backups
D.Are able to back up specific items within a database
E.Create automatically compressed backups
F.Will lock all storage engines for duration of backup