LOB data is not cached in buffer pools. When a LOB is retrieved from the database, the data is obtained directly from the storage device. DB2 refers this operation as direct read. On the other hand when a LOB is written to the database, DB2 performs a direct write operation.
Select the three actions on this page in order to illustrate direct read and write activities happening with LOB data.
SELECT DIRECT_READS, DIRECT_WRITES
FROM SYSIBMADM.SNAPDB
SYSIBMADM.SNAPDB is an adminstrative view to retrieve snapshot information of the database. There are a number of different snapshot monitor SQL administrative views available. Each returning monitor data about a specific area of the database system.
The administrative view used above contains database level information and counters for the currently connected database.
SELECT VIEW_TEXT, COLUMN_TEXT
FROM LOBDATA