Update & select query when tablespace in backup mode

Question

Hi,
I have a query related to the DML statement when tablespace is in backup mode. Suppose when put the tablespace in begin backup mode then during the time one user run an update statement against this tablespace and commit the transaction and other user run the select query on the same data then which image the user will get and from where the data will be taken to display.
steps:
alter tablespace users begin backup;
update emp set sal=4000 where empno=101;
commit;
select * from emp where empno=101;
Now what result user will get and from where the data will fetch.
Thanks,
Gulshan

Answer 1

Hi,
alter tablespace users begin backup;
update emp set sal=4000 where empno=101;
commit;
select * from emp where empno=101;AFAIK, the database would work normally and you will not find the difference from transactions perspective. If you check from Oracle architecture and process, fuzzy bit will be setted at up and additional redo vectors would be saved up in the online redo logs - due to which size of redo would higher when compared to normal transactions. Secondly, you must be worried about the backup - which might not be consistent. So better opt for RMAN instead of User managed Backups.
- Pavan Kumar N