If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

 
Go Back  dBforums > Database Server Software > DB2 > Bufferpool for Index and tables

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #1 (permalink)  
Old 09-28-07, 08:53
sahana sahana is offline
Registered User
 
Join Date: Sep 2003
Posts: 36
Bufferpool for Index and tables

I understand that most of the db2 shops use 2 different buffer pool, one BP for the tablespace and one BP for the indexspace. Just would like to know what is the purpose and the benefit of the same.

Regards
Sahana
Reply With Quote
  #2 (permalink)  
Old 09-28-07, 09:32
rahul_s80 rahul_s80 is offline
Registered User
 
Join Date: Jul 2006
Location: Pune , India
Posts: 433
correct me if i am wrong ... but i think
you can have two different tablespaces for tables and indexes and these tablespaces are releated to bufferpools
__________________
Rahul Singh
Certified DB2 9 DBA / Application Developer
Reply With Quote
  #3 (permalink)  
Old 09-28-07, 09:42
Marcus_A Marcus_A is offline
Registered User
 
Join Date: May 2003
Location: USA
Posts: 5,196
The theory of having 2 (or more) different bufferpools is that you want indexes (and small frequently used tables) in the bufferpool at all times (100% buffer pool hit ratio). This is usually feasible if the same bufferpool is not shared with large tables (the size of the bufferpool would as large, or nearly as large. as the sum of all the objects using it).

Then larger tables (and maybe indexes for extremely large tables) would be placed in another bufferpool that would have a lower bufferpool hit ratio, since it is not feasible to make the bufferpool large enough to hold all of the larger tables.

However, if you have a small database, and everything will fit into one bufferpool, then it doesn't matter and you can put everything in the default bufferpool (and you can use SMS).

In order to have indexes seperated from tables in different bufferpools, you need to use DMS tablespaces and put indexes in a different tablespces in the create table statement (INDEXES IN xxxxxx clause).
__________________
M. A. Feldman
IBM Certified DBA on DB2 for Linux, UNIX, and Windows
IBM Certified DBA on DB2 for z/OS and OS/390
Reply With Quote
  #4 (permalink)  
Old 10-02-07, 11:37
sahana sahana is offline
Registered User
 
Join Date: Sep 2003
Posts: 36
Thanks Marcus. Your reply came as an eye opener for me. I understood it better.
thanks
Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On