Faster Updates

Question

Is there some kind of Optimizer Hint which can be used to avoid generating Rollback Information when updating a Table . The Table which i have is A GLOBAL TEMPORARY TABLE WHICH does not allow a NOLOGGING OPTION with the Create Table clause. There is around 10 million rows to be updated in one single update block.
example
UPDATE SALES_FORECAST_MASTER
SET A = ( )
Here Sales_Forecast_Master has 10 million rows and is A GLOBAL TEMPORARY TABLE.
Thanks
Ravi

Answer 1

Watch :
SQL> create table t1n (col1 integer) nologging;
Table created.
SQL> create global temporary table t1x (col1 integer);
Table created.
SQL> insert into t1x select rownum from all_objects;
32448 rows created.
Statistics
25 recursive calls
33189 db block gets
229155 consistent gets
0 physical reads
4039700 redo size
863 bytes sent via SQL*Net to client
578 bytes received via SQL*Net from client
3 SQL*Net roundtrips to/from client
2 sorts (memory)
0 sorts (disk)
32448 rows processed
SQL> insert into t1n select rownum from all_objects;
32448 rows created.
Statistics
129 recursive calls
482 db block gets
229194 consistent gets
0 physical reads
501916 redo size
864 bytes sent via SQL*Net to client
578 bytes received via SQL*Net from client
3 SQL*Net roundtrips to/from client
2 sorts (memory)
0 sorts (disk)
32448 rows processed
So the normal nologging generates less redo
Now let's do an update :
SQL> update t1x set col1=2;
32448 rows updated.
Statistics
24 recursive calls
33198 db block gets
64 consistent gets
0 physical reads
4824780 redo size
863 bytes sent via SQL*Net to client
553 bytes received via SQL*Net from client
3 SQL*Net roundtrips to/from client
1 sorts (memory)
0 sorts (disk)
32448 rows processed
SQL> update t1n set col1=2;
32448 rows updated.
Statistics
24 recursive calls
33200 db block gets
67 consistent gets
0 physical reads
7680972 redo size
864 bytes sent via SQL*Net to client
553 bytes received via SQL*Net from client
3 SQL*Net roundtrips to/from client
1 sorts (memory)
0 sorts (disk)
32448 rows processed
SQL>
and now we see the normal table generating more redo on an update.