| Some Question .. i m new in Oralce [message #53352] |
Sun, 15 September 2002 06:27  |
jagjeet singh
Messages: 16
Registered: October 2001
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Junior Member |
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hello friends .. i m new in oracle .. and trying to learn oracle .. pls help me
background process writes when ..
1 .. What is dirty buffer threshold reached ....
2 .. Table truncate or drop .. ( but if our tablespace is localy manage and i issue a
command truncate table ... there are no dictionary update required .... so y Dbwr will write
....
3 .. when dbwr writes data in data files log writer also write .. and oracle maintaing commited
and uncommited transaction at two files ..
4 .. when i issued .
Show Sga
Total System Global Area 3643764 bytes
Fixed Size 6543794 bytes
Variable Size 19521536 bytes
i think Total System Global Area = max_sga_size
mean does oracle reserved the memory which we define for max_sga_size .....
and what is Fixed size ....
and what is vaiable size
5 .. if a database is in read only mode .. does it writes or update the control files ... ?
6 .. i m managing a database without any password file .. using os authentication ..
when i grant sysdba to a user where it stores the the info ....
thanx in advance ..
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| Re: Some Question .. i m new in Oralce [message #53371 is a reply to message #53352] |
Mon, 16 September 2002 12:06  |
Trifon Anguelov
Messages: 514
Registered: June 2002
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Senior Member |
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Very good questions for someone new to Oracle. Keep up your curriosity the same way !!!!
4. Answers are Here
6. All user privileges and roles, including SYSDBA, SYSOP are kept hashed in the database dictionary tables. Query DBA_USERS to see the hashed passwords, or DBA_ROLES, DBA_ROLE_PRIVS for roles and privileges.
3. LGRW writes ONLY the commited transactions in the redo log files. The uncommited transactions are kept in the rollback segments, until they are either commited or rolled back.
5. In read-only mode - Oracle doesn't apply any archived logs, doesn't do chackpoints or redo log switches - all which will make the control file to be updated. The answer is in read-only mode the control file is not updated.
I am having hard time to understand the rest of your questions. Can you try to clarify them?
Hope that helps,
clio_usa
OCP - DBA
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