Insert taking long time

Hi Gurus,

We have an insert statement called by a script that runs daily once from LIVE production to second database over dblink. Both databases were on 10.2.0.3.0 till recently. Last month we upgraded production to 11.2.0.4. Since then this insert statement takes hours to even insert 1 row.

INSERT INTO STAGING.FIX_VACANCY_EXCEPTIONS SELECT * FROM VACANCY@REMOTE WHERE VAC_REF IN(SELECT VAC_REF FROM STAGING.VACANCY_CC MINUS SELECT VAC_REF FROM PROD.VACANCY).

Could someone throw some light why this behaviour.

Reg

Raj