update takes time.

This update statement takes more than 2hrs. It updates 3 lakh record.  I can not turn the query since it is delivered query. Is the anyway i can improve the performance.

As of now PS_JRNL_LN_TAO4 table stats was locked with 500 rows. Db level dynamic sampling is set to 2.

UPDATE PS_JRNL_LN

    SET foreign_amount =

           (SELECT monetary_amount

              FROM PS_JRNL_LN_TAO4

             WHERE business_unit = PS_JRNL_LN.business_unit

               AND journal_id = PS_JRNL_LN.journal_id

               AND journal_date = PS_JRNL_LN.journal_date

               AND journal_line = PS_JRNL_LN.journal_line)

  WHERE process_instance = 000000000