[多选] The RVPC user can do which of the following？（）

Which three statements about performance analysis by SQL Performance Analyzer are true? （） It detects changes in SQL execution plans.。 It produces results that can be used to create the SQL plan baseline.。 The importance of SQL statements is based on the size of the objects accessed.。 It generates recommendations to run SQL Tuning Advisor to tune regressed SQLs.。 It shows only the overall impact on workload and not the net SQL impact on workload.。 准备工作 A client wants to implement a highly available cluster between two sites. At each site the client has an IBMDS8300. At each site， the client would like a single node which will be connected through a SAN to the local DS8300but not the remote DS8300. Which clustering product could be used to provide high availability for this infrastructure？（） PowerHA/XD for GLVM。 PowerHA with cross-site LVM。 PowerHA/XD for Metro Mirror。 PowerHA/XD for Global Mirror。 You work as a database administrator for Supportcenter.cn. When you tried to connect to the database， you received the following error：   ERROR：   ORA-12541：TNS：no_listener   You found that the listener is not running on the server， so you issued the following command in the Listener Control utility to start the listener.   lsnrctl>START   What statement is true？（） It would attempt to start the default listener。 It would start the most recently created listener.。 It would display an error with a message asking for the listener name to be specified.。 It would show you a list of listeners and prompts for the listener name that you want to start.。 Which constraint can be defines only at the column level? （） UNIQUE。 NOT NULL。 CHECK。 PRIMARY KEY。 FOREIGN KEY。 The RVPC user can do which of the following？（）