单项选择题 The SPFILE for the PROD database specifies the following initialization parameter values：   SGA_TARGET = 2G   DB_8K_CACHE_SIZE = 128M   You create a tablespace named HR with the non-standard block size of 8K. Four database users are running queries on a table in the HR tablespace. These users complain that the queries are taking longer than usual to complete. While investigating the reasons for this delay， you discover that the database encounters extensive cache misses on the database buffer cache with the block size of 8K. You issue the following statement to increase the value of the DB_8K_CACHE_SIZE initialization parameter to 256M：   SQL>ALTER SYSTEM SET DB_8K_CACHE_SIZE=256M SCOPE = BOTH；   What is the result of this statement？（）

单项选择题 You recently created a database and configured the SPFILE with the following parameter settings to ensure that Oracle automatically adjusts the memory for the Program Global Area （PGA）：   SORT_AREA_SIZE = 150M   HASH_AREA_SIZE = 150M   BITMAP_MERGE_AREA_SIZE = 150M   CREATE_BITMAP_AREA_SIZE = 150M   WORKAREA_SIZE_POLICY = AUTO   You have not included the PGA_AGGREGATE_TARGET initialization parameter in the SPFILE and the System Global Area （SGA） is currently sized at 4G.   What is the total PGA memory allocated across all database server processes？（）

单项选择题 You recently added a third-party application to your database and do not have access to the SQL code of this application. Database users are complaining of performance-related issues， such as increased time required to complete a query. While investigating， you discover from the STATSPACK utility that some of the memory structures have low hit ratios. You plan to resize some of the memory structures by using the Memory Advisor. For which memory structure will you fail to obtain optimal settings by using the Memory Advisor？（）