Oracle OCA 1Z0-042 第46题疑问 optimizer statistics

Oracle OCA 1Z0-042 第46题疑问

You work as a database administrator for Certkiller.com. In your transaction application, you have scheduled a job to update the optimizer statistics at 05:00 pm every Friday. The job has successfully complited. Which three pieces of information would you check to confirm that the statistics have been collected? Choose three

A. Average row size
B. Last analyzed date
C. Size of table in bytes
D. Size of table in database blocks
E. Number of free blocks in the free list
F. Number of extents present in the table.

答案是A B D

 

今天在文献中找到答案：


Optimizer statistics are a collection of data that describe more details about the database and the objects in the database. These statistics are used by the query optimizer to choose the best execution plan for each SQL statement. Optimizer statistics include the following:

Table statistics

Number of rows
Number of blocks
Average row length
Column statistics
Number of distinct values (NDV) in column
Number of nulls in column
Data distribution (histogram)

Index statistics
Number of leaf blocks
Levels
Clustering factor
System statistics
I/O performance and utilization
CPU performance and utilization



所以  自我   觉得 答案 是   对地  ！