ushodaya

• May 20th, 2018

 

We should generate statistics for all tables and clusters and all types of indexes accessed by your SQL statements before using the cost-based approach. If the size and data distribution of your tables change frequently, then you should generate these statistics regularly to ensure the statistics accurately represent the data in the tables.
Oracle generates statistics using the following techniques:
Estimation based on random data sampling
Exact computation
User-defined statistics collection methods

Shivam Softa

• Sep 19th, 2018

 

Helps Oracle engine to create better execution plan to execute the query.