- Enhanced configuration of archive deletion policies
Archive can be deleted , if it is not need DG , Streams Flashback etc
When you CONFIGURE an archived log deletion policy applies to all archiving destinations, including the flash recovery area. BACKUP ... DELETE INPUT and DELETE... ARCHIVELOG use this configuration, as does the flash recovery area. When we back up the recovery area, RMAN can fail over to other archived redo log destinations if the flash recovery area is inaccessible.
- Configuring backup compression
In 11g can use CONFIGURE command to choose between the BZIP2 and ZLIB compression algorithms for RMAN backups.
- Active Database Duplication
Now DUPLICATE command is network aware i.e.we can create a duplicate or standby database over the network without taking backup or using old backup.
- Parallel backup and restore for very large files
RMAN Backups of large data files now use multiple parallel server processes to efficiently distribute theworkload for each file. This features improves the performance of backups.
- Improved block media recovery performance
RECOVER command can recover individual data blocks.
RMAN take older, uncorrupted blocks from flashback and the RMAN can use these blocks, thereby speeding up block media recovery.
- Fast incremental backups on physical standby database
in 11g we can enable block change tracking on a physical standby database (ALTER DATABASE ENABLE/DISABLE BLOCK CHANGE TRACKING SQL statement).This new 11g feature enables faster
incremental backups on a physical standby database than in previous releases.because RMAN identifywe the changed blocks sincethe last incremental backup.
Friday, April 13, 2007
Thursday, April 12, 2007
alter system set log_archive_dest_1='SERVICE=standby1
check where there compression is enabled or not
select dest_name , compression from v$archive_dest
compression column will show enable if it is enable.
Wednesday, April 11, 2007
It is now possible to query a physical standby database while Redo Apply is active.This new capability increases your return on investment in Data Guard technology because a physical standby database can now be used to offload queries from the primary database in addition to providing data protection.
( We can do same with logical standby , what is diffrent here , well redo apply method is faster in physical stand by ie redo apply methode is diffrent in physical standby)
- Stop log apply
Alter database recover managed standby database cancel;
- open database for read-only access
alter database open
- Once daabase open start redo apply
alter database recover managed standby database
using current logfile disconnect from session;
Tuesday, April 10, 2007
Automatic Memory Management ( Oracle 11g New Features)
Well in 10g SGA can be auto tune and 11g it extended to PGA as well ie SGA and PGA both can auto tune
( i would say , i understood this much only
11g memory management = SGA auto tune + PGA auto tune )
For auto memory, we need to set parameter MEMORY_TARGET and MEMORY_MAX_TARGET. Parameter MEMORY_TARGET is dynamic, we can change the target memory size at any time without restarting the database. The MEMORY_MAX_TARGET serves as an upper limit so that we cannot by mistake set the MEMORY_TARGET size too high. Because certain SGA components eithercannot easily shrink or must remain at a minimum size, the database also prevents you from setting thetarget memory size too low.
If MEMORY_TARGET is set to a non-zero value:
- If SGA_TARGET and PGA_AGGREGATE_TARGET are set, they will be considered the min value for the sizes of SGA and the PGA respectively. MEMORY_TARGET can take values from SGA_TARGET + PGA_AGGREGATE_TARGET to MEMORY_MAX_SIZE.
- If SGA_TARGET is set and PGA_AGGREGATE_TARGET is not set, we will still auto-tune both parameters. PGA_AGGREGATE_TARGET will be initialized to a value of (MEMORY_TARGET-SGA_TARGET).
- If PGA_AGGREGATE_TARGET is set and SGA_TARGET is not set, we will still auto-tune both parameters. SGA_TARGET will be initialized to a value of min(MEMORY_TARGET-PGA_AGGREGATE_TARGET, SGA_MAX_SIZE (if set by the user)) and will auto-tune subcomps.
Monday, April 9, 2007
One can create Invisible Indexes to test performance or convert existing index into Invisible Indexe to check impact.
Optimizer not consider invisible indexes , we need to specify explicity with hint.Making an index invisible is an alternative to making it unusable or dropping it. Unlike unusable indexes, invisible indexes are maintained during DML statements.
CREATE INDEX I_emp_ename ON emp(ename)
STORAGE (INITIAL 10K NEXT 10k PCTINCREASE 50)
ALTER INDEX I_emp_ename INVISIBLE;
ALTER INDEX I_emp_ename VISIBLE;
SELECT INDEX_NAME, VISIBILITY FROM USER_INDEXES
WHERE INDEX_NAME = 'I_EMP_ENAME';