Re: explain plan and the real execution plan

In addition, if the queries against this table recently started to 
use columns not used before, the content of col_usage$ will change 
thus affecting the stats related to auto generated historgram.

Yong Huang

Tanel Poder wrote:

> 1)       The optimizer statistics
>
> I assume this database has no change – no ddl and dml. Under this
> situation, I would say the optimizer statistics would remain the same,
> correct?

Even if you have no DDL and no DML happening, someone may still have
gathered optimizer statistics on the tables and changed them. Maybe the last


      
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