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diff. between checkpoint and DBWn
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| rohit1346 2002-04-08, 2:27 am |
| whats the exact difference between a checkpoint and a DBWn process? | |
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| a checkpoint is an event and DBWn process is a process that writes to the database files.
Basicaly think of a checkpoint as an interval time that your Oracle server decides it is going to write all of the buffer contents to disk and time stamp it all.
The DBWn process is involved in a checkpoint as it writes contents of the DB buffer to the physical database files.
Theres a bit more to it than that and I'm sure someone else will elaborate but thats basically the difference. | |
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| Checkpoint is the tab on a script, until which you can commit, rollback your work.
eg.
select * from emp where dept_id = 20;
create view as_view as select empname, dept_id,job from emp where dept_id = 10;
create savepoint e1;
select * from sales where dept_id = 10;
drop table sales;
create savepoint e2;
Now we can commit the transaction upto e1 or rollback the operation till e1. Also if you have not commited the transaction till e2 you can rollback upto e2.
rollback e2;
will rollback those statements issued from e1 to e2.
Whereas the other option is a Database process in the background which writes data into the datafiles.
srine | |
| rohit1346 2002-04-08, 5:22 am |
| Thanks ian and tvst, however, I didn't get the meaning of Tvst's post.. I didn't get to what exactly he is pointing to... | |
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| tvst, a savepoint is totaly unrelated a checkpoint. | |
| aneesh_bhatia 2002-04-08, 11:55 pm |
| I have no clue what tvst is talking about! I think Ian_J has hit the nail on the head. If you need furhter clarification, look for the admin document on the Oracle website, it is very comprehensive.
Cheers! |
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