oracle slow query with diferent user I have a question with an oracle query that takes almost 20 minutes when it is executed from a schema and yet when it runs as sys users it runs in 1 second maximum ... how is this possible? ... I do not know much about tuning plsql and I find it difficult to find the cause of this tremendous delay, I would like to know if there is any tool to autotuning the queries. The sentence in question is:

SELECT FC.ID_SER 
     FROM MIGER.FONT_COUNTER FC
     WHERE TO_CHAR(FC.ID_SER) NOT IN (SELECT 
     ID_SER FROM INAC.SERV)
     -- AND (FC.STATE &lt;&gt;'R' OR FC.STATE &lt;&gt; NULL)
     AND FC.T_ACT='M'


Thank you
In past I noticed that query plan could be different, because of the Locale (language) being used on the client. Mostly the locale is enherited from client OS.