Blocked vs. non-blocked pages

What is the difference between blocked and non-blocked pages in a bufferpool and how do they affect performance?

Thank you in advance.
aporrasAsked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

ghp7000Commented:
Block based bufferpools allow performance improvement for sequentail prefetching. From the db2 docs:
A block-based buffer pool consists of both a page area and a block area. The page area is required for non-sequential prefetching workloads. The block area consists of blocks where each block contains a specified number of contiguous pages, which is referred to as the block size (normally pages are read into the bufferpool by reading contiguous pages on disk into non contiguous pages in memory).
When a block based buffer pool is available, the prefetching code recognizes this and will use block I/Os to read multiple pages into the buffer pool in a single I/O significantly improving the performance of prefetching. The BLOCKSIZE parameter of the CREATE and ALTER BUFFERPOOL SQL statement defines the size of the blocks, and hense the number of pages read from disk in a block I/O.


0
aporrasAuthor Commented:
I'm still not sure what the difference is between blocked and non-blocked pages... and if I am understanding your comment there would never be any value in non-blocked pages yet when looking at the GUI in DB2 UDB 8.2, it defaults to all pages in a bufferpool being non-blocked.
0
ghp7000Commented:
yes that is the default setup , you have to explicitly create the block based bufferpools with alter bufferpool or with create bufferpool .....NUMBLOCKPAGES  ... BLOCKSIZE     keywords

the difference is the way in which the data pages are read into the bufferpool
0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
DB2

From novice to tech pro — start learning today.

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.