Locks are used to protect the data or resourses from the simulteneous use of them by multiple sessions which might set them in inconsistant state… Locks are external mechanism, means user can also set locks on objects by using various oracle statements.
Latches are for the same purpose but works at internal level. Latches are used to Protect and control access to internal data structres like various SGA buffers.They are handled and maintained by oracle and we can’t access or set it.. this is the main difference
Issue:
Database is in Flashback Mode.
Enabled No logging on some db Tables
Recover the database.
Truncate those no logging Temporary tables.
Now we get error message ORA-1578: ORACLE data block corrupted
Reason:
Oracle says it is a behavior in 10g and fixed in 11g Rel1.
Cannot Reuse a Corrupt Block in Flashback Mode, ORA-1578 [ID 729433.1]
In 11g (11.1 releases) there is an optimization introduced to skip the block read if the object was dropped before the flashback retention range, and this will help with corrupt blocks on disk.
Issue 1:
Intially Flashback Database was enabled but noticed Flashback was disabled automatically long time ago.
Reason:
It could be because the flashback area 100%
Once Flashback Area become 100% full then oracle will log in Alert that Flashback will be disabled and it will automatically turn off Flash Back without user intervention.
ASM Limitation
ASM has the following size limits:
• 63 disk groups in a storage system
• 10,000 ASM disks in a storage system
• 1 million files for each disk group
It depends on how you killed the process.
If you did and alter system kill session you should be able to look at the used_ublk block in v$transaciton to get an estimate for the rollback being done.
If you killed to server process in the OS and pmon is recovering the transaction you can look at V$FAST_START_TRANSACTIONS view to get the estimate
The database is logically divided into one or more tablespaces.
For each tablespace we explicitly create one or more datafiles.
bring the database to the mount state
sql>alter database create datafile ;
sql>recover datafile ;
sql>alter database open;
In Linux, Unix the command: ps -ef|grep pmon
In Windows: services.msc
You have lost datafiles and you dont have backup and database is not running in archive log mode……
So we need to recreate the datafiles which will be empty….. you can not recover, becuase you dont have backup and database not in archive log mode
I have attended Ask Tom Live seminar about 11g Rel2 at Tokyo, Japan. Do you believe it I have got an opportunity to take a snap with him. I am very happy to share with you.