| extent management [message #125359] |
Fri, 24 June 2005 12:29  |
balavignesh
Messages: 180
Registered: March 2005
|
Senior Member |
|
|
hai,
i have a doubt.
could u plz state the extent management in 8i and 9i(release 1 and 2) either local or dictionary managed...? in addition to that what type of management is used in system tablespace..in each of version and releases specified..?
bala
|
|
|
|
|
|
|
|
| Re: extent management [message #130552 is a reply to message #130540] |
Mon, 01 August 2005 01:10  |
girish.rohini
Messages: 744
Registered: April 2005
Location: Delhi (India)
|
Senior Member |
|
|
HI
This statement means that all extent allocation related information is kept in data dictionary tables in case of Dictionary managed tablespaces. This means whenever extent allocation/deallocation takes place inside a tablespace these dictionary tables are accessed.
Regds
Girish
|
|
|
|
| Re: extent management [message #130600 is a reply to message #125359] |
Mon, 01 August 2005 07:14 |
smartin
Messages: 1803
Registered: March 2005
Location: Jacksonville, Florida
|
Senior Member |
|
|
edcas, that is a fair question. As Girish mentioned, oracle has to track what space is available in each tablespace. In dictionary managed, this tracking all take place in the system tablespace, where the data dictionary resides. The problem is that this creates a single, database-wide point of contention. The actions of tablespace 1 impact the actions on tablespace 2.
But in locally managed, all of this is tracked at the tablespace (local) level. This means that actions that affect tablespace 1 only affect tablespace 1. Less contention.
Also, locally managed lets you do things like set a fixed, uniform size extent size for the tablespace, which allows you to control fragmentation and allocation issues that can become problems in dictionary managed tablespaces.
Basically, locally managed tablespaces are the way to go, and are the only thing you'll use on later versions. Lots more has been written about this elsewhere, but chapter 3 of the 10g concepts guide talks about it some more, but not too much because by now it is assumed everyone will be locally managed. The 9i concepts guide chapter may discuss it further.
Here is the 10g chapter:
http://download-west.oracle.com/docs/cd/B14117_01/server.101/b10743/physical.htm#i2006
|
|
|
|
|
|
] 
Blog
Search
Help
Members
Register
Login
Home
