Question

1. Select all of the following that the database maintains statistics on at the column level:

   	A.	Data Range
   	B.	Null Values
   	C.	Number of Blocks
   	D.	Number of distinct values
   	E.	Data distribution
   	F.	Data Type conflicts
   	G.	Number of Rows

Answer 1

The database maintains following category wise statistics on at column level:-  

1. Table statistics

i) Number of blocks

ii) Number of rows

iii)Average row length

2.System statistics

i)CPU performance and utilization

ii)I/O performance and utilization

3.Column statistics

i)Number of nulls in the column

ii)Number of distinct values in column

4.Index statistics

i)Levels

ii)Number of leaf blocks

iii)Clustering factor

All the above-mentioned statistics are optimizer statistics that mean all are created just for query optimization.

So the correct option will be (B),(C),(D) and (G)