Update tuning

Question

UPDATE SALES_BISC BISC
SET STATUS_FLAG= 'M'
WHERE BISC.MAT_CD NOT IN
(SELECT LP.MAT_CD FROM mat_lp LP
WHERE LP.orgid = BISC.orgid
AND LP.distrid = BISC.distrid
AND LP.lang1='EN'
rewriting the query in the following format --- Results in 01779 Error
UPDATE
(SELECT
BISC.mat_cd,
BISC.STATUS_FLAG
from
SALES_BISC BISC,
mat_lp LP
WHERE LP.orgid = BISC.orgid
AND LP.distrid = BISC.distrid
AND LP.lang1='EN'
AND LP.mat_cd = BISC.mat_cd
AND LP.mat_cd IS NULL
SET STATUS_FLAG= 'M';
Rewriting the query in the below mentioned way --- Updates 0 rows when there are rows to be updated.
UPDATE SALES_BISC BISC
SET STATUS_FLAG='M'
WHERE NOT EXISTS
(SELECT LP.MAT_CD FROM mat_lp LP
WHERE LP.orgid = BISC.orgid
AND LP.distrid = BISC.distrid
AND LP.lang1='EN');
ANY IDEA HOW TO MAKE OT BETTER.
As I will be using this to update a MILLION ROWS on a everyday basis for 4 months.

Answer 1

user12870000 wrote:
rewriting the query in the following format --- Results in 01779 ErrorThis is a sign that your mat_lp table is lacking an important unique constraint. This constraint could tell Oracle that by updating the join query is safe because every row in sales_bisc leads to at most 1 row after joining it to mat_lp.
If you can define that unique constraint on mat_lp, then you have the most efficient update statement written already. If not, can you post the definition of those tables including the constraints and indexes?
Regards,
Rob.