What's the best way to delete 2.4 million of records from table?

Question

We are having two tables one is production one and another is temp table which data we want to insert into production table. temp table having 2.5 million of records and on the other side production table is having billions of records. the thing which we want to do just simple delete already existed records from production table and then insert the remaining records from temp to production table.
Can anyone guide what's the best way to do this?
Thanks,
Waheed.

Answer 1

Waheed Azhar wrote:
production table is live and data is appending in this table on random basis. if i go insert data from temp to prod table a pk voilation exception occured bcoz already a record is exist in prod table which we are going to insert from temp to prod
If you really just want to insert the records and don't want to update the matching ones and you're already on 10g you could use the "DML error logging" facility of the INSERT command, which would log all failed records but succeeds for the remaining ones.
You can create a suitable exception table using the DBMS_ERRLOG.CREATE_ERROR_LOG procedure and then use the "LOG ERRORS INTO" clause of the INSERT command. Note that you can't use the "direct-path" insert mode (APPEND hint) if you expect to encounter UNIQUE CONSTRAINT violations, because this can't be logged and cause the direct-path insert to fail. Since this is a "live" table you probably don't want to use the direct-path insert anyway.
See the manuals for more information: http://download.oracle.com/docs/cd/B19306_01/server.102/b14200/statements_9014.htm#BGBEIACB
Sample taken from 10g manuals:
CREATE TABLE raises (emp_id NUMBER, sal NUMBER
   CONSTRAINT check_sal CHECK(sal > 8000));
EXECUTE DBMS_ERRLOG.CREATE_ERROR_LOG('raises', 'errlog');
INSERT INTO raises
   SELECT employee_id, salary*1.1 FROM employees
   WHERE commission_pct > .2
   LOG ERRORS INTO errlog ('my_bad') REJECT LIMIT 10;
SELECT ORA_ERR_MESG$, ORA_ERR_TAG$, emp_id, sal FROM errlog;
ORA_ERR_MESG$               ORA_ERR_TAG$         EMP_ID SAL
ORA-02290: check constraint my_bad               161    7700
(HR.SYS_C004266) violatedIf the number of rows in the temp table is not too large and you have a suitable index on the large table for the lookup you could also try to use a NOT EXISTS clause in the insert command:
INSERT INTO <large_table>
SELECT ...
FROM TEMP A
WHERE NOT EXISTS (
SELECT NULL
FROM <large_table> B
WHERE B.<lookup> = A.<key>
);But you need to check the execution plan, because a hash join using a full table scan on the <large_table> is probably something you want to avoid.
Regards,
Randolf
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