LOB - no file system caching

L_DBA_L · #1 (**permalink**) 08-22-10, 19:25

LOB does not use DB2 buffer pool. Where is it cached if a table space is created with NO FILE SYSTEM CACHING on DB2 9.5.5 for Linux?

dr_te_z · #2 (**permalink**) 08-23-10, 01:57

Nowhere, like you specified

L_DBA_L · #3 (**permalink**) 08-23-10, 19:37

How and where DB2 updates LOB data if it's cached nowhere?

stolze · #4 (**permalink**) 08-24-10, 12:21

The data is stored on disk. So it is updated there.

Caching is a mechanism to speed up the access to some data. It is a different concept than data modifications.

L_DBA_L · #5 (**permalink**) 08-24-10, 22:10

Can DB2 skip caching regular data in the buffer pool and update it directly on disk?

stolze · #6 (**permalink**) 08-25-10, 16:03

What has a buffer pool to do with updating data? You open a file and write to it -> you changed the data in the file. The buffer pool in a database system and the associated page flushers/prefetchers are just there to do memory operations instead of read/write in order to improve performance.