2、Which two are true about Optimizer Statistics?
? A) They do not persist across Instance restarts.
? B) They are automatically updated when DDL statements execute.
? C) They are gathered by the Manageability Monitor (MMON) background process.
? D) They can be gathered by executing the PL/SQL procedures in the DBMS_STATS package.
? E) They can be used to determine the events on which a database instance waited.
? F) They provide Information to the Optimizer so that it can determine optimal execution plans for SQL statements.
? Answer:DF
阅读(847) | 评论(0) | 转发(0) |
