Why doesn't the Oracle optimizer use my index?
Querying too much data
Most Oracle developers know that an index is useful when you can use it to restrict your result set to a small number of the total rows in a table.
So, the obvious side…
Note: this article covers simple compression. Oracle introduced in version 11g release 2 a new feature called Advanced Compression which is not covered here.
General principle of Oracle compression
Oracle compression is a way of reducing the d…