Difference between oracle 9i, 10g, 11R1 and 11R2.

Below table brief out the difference in brief between oracle database versions 9i, 10g, 11gR1 and 11gR2.

9i	10g	11gR1 or 11.1	11gR2 or 11.2
PGA_AGGREGATE_TARGET parameter was introduced to automate the pga management.	SGA_TARGET was introduced to automate the SGA management.	MEMORY_TARGET was introduced to automate the management of both SGA and PGA
High availability using cluster.	Grid computing. VIP		SCAN, CTSS Storage of OCR and voting disk in ASM. GPNP service which eases the removal and addition of RAC nodes. Oracle Restart service to provide HA for single instance database.
Introduced DataGuard	DataGuard Realtime apply and log compressions Max no of standby dbs are 10	Snapshot standby	Active DataGuard Also, automatic block repair in active dataguard. New rman policy: CONFIGURE ARCHIVELOG DELETION POLICY TO APPLIED ON ALL STANDBY. Max no of standby dbs are 30
Traditional exp/imp	Data Pump
	SYSAUX tablespace
	ADDM and AWR
patching takes minutes.	patching takes few seconds	Online patching
	ASM	SYSASM privilege Asmcmd Also, new disk group compatibility attributes that are compatible.rdbms and compatible.asm which enables hetrogenous environments i.e. disk groups from both 10g and 11g.	cp command in asm
	Automatic UNDO tablespace management.
	Backup compression in Rman
Default temporary tablespace	Rename temporary tablespace		Shrink temporary tablespace
background_dump_destination		diagnostic_destination

Regards

Vineet Arneja