have been thinking of ways around it and have found converting the primary key id of the target table to use an auto-increment trigger prevents the gap happening… z(i) from dual) T2 ON (T1.x = T2.x) WHEN NOT MATCHED insert WHEN MATCHED update This runs very poorly compared to SAVE Exceptions insert and then processing the errors (dup-key) for update Is there a limit to how high the Bulk_Limit can be for such an operation Regards You mentioned in the “Watch out for these when you MERGE’ No.4 about the delete clause, which is not entirely true.
although will have to see how this affects performance! You should refer to the following article, https://oracle-base.com/articles/10g/merge-enhancements-10g The Delete Clause section hi, i have a scenario, can you tell me how to use MERGE, i have source table(s1) and destination table (d1), my requirement is i get incremental data to s1 on daily basis.
Consider another table STUDENT_N, which holds updates for the target table STUDENT.
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create or replace procedure ups(xa number) as begin merge into mergetest m using dual on (a = xa) when not matched then insert (a,b) values (xa,1) when matched then update set b = b 1; end ups; / drop table mergetest; create table mergetest(a number, b number); call ups(10); call ups(10); call ups(20); select * from mergetest; A B ---------------------- ---------------------- 10 2 20 1 Apparently the "merge into" statement is not atomic.
It can result in "ORA-0001: unique constraint" when used concurrently.
When matched, set transaction_type = ‘U’, when not matched, set it to ‘I’. After running MERGE, select the ids based on transaction type. That’s then 2 queries; in my case I have just to treat one row at a time (update 1 or insert 1) so the simplest for me is probably to do a fist get query to check if the row already exists and then depending on the result do an insert or an update (in both cases the RETURNING clause works fine. PS: just fyi, my app has to support several SQL servers and in My Sql it’s much simpler: 1 single query thanks to the “ON DUPLICATE KEY UPDATE” instruction.
Hmmm…looks like you’ll have to do the traditional INSERT/UPDATE as you say.
select * from student; ID NAME SCORE ---------- --------------- ---------- 1 Jack 540 2 Rose 3 William 650 4 Caledon 620 5 Fabrizio 600 6 Thomas 7 Ruth 690 11 Brock 705 10 Lizzy 9 Wallace 600 8 Spicer 620 11 rows selected. Thanks, Hi egavaldo, MERGE doesn’t support the RETURNING clause and going by this Ask Tom thread, the feature isn’t likely to be available anytime soon.