The three first executions of a query return different results. Result Cache bug?

Hi,

We work with Oracle 11g Enterprise Edition release 11.1.0.7.0. We remark a "temporary inconsistent data" problem. The three first executions of a query return different results.

Every day we load new data in a datawarehouse. When we check the new data of the fact table with a basic query, the result alter three times before it comes right. Then it stays fixed. The problem can't be reproduced. Only a fact column is affected by this problem. This column was inserted after the creation of the table (ALTER tab ADD column…).

I can't understand how the data is in the DB but is not directly return after the first query run. Is it possible that the "Result Cache" had a bug?