If we define lob or blob with some specific size, but if it uses only few for somw rows not the full size, does db2 consume full size or whatever allocated ?

( For example in case of varchar(10) ,if you insert only 5 letter string like 'abcde' it only consumes varchar(5) , does this appy to lob/clob/blob also ? )

TIA.

IIRC, it will occupy only the required amount of disk space

Cheers
Sathyaram

Keep in mind that DB2 does not use bufferpools for LOB data, so all reads and writes are synchronous I/O to disk. It is better to use varchar if possible to store such objects unless they will not fit, or performance is not important. I have clearly seen a degradation in performance with tables that have LOB columns using SQL Statement Monitoring snapshots.

for lob is there any specific bufferpoold should be created ?
what is your experience ?
TIA.

You probably could create a separate tablespace for your LOBS using file containers - in that case the file system cache will help.

I don't think that DB2 can use bufferpools for LOB objects, becasue they are too large and don't fit in 4K, 8K, 16K, or 32K chunks.

In fact, the LOB objects for the DB2 catalog are stored in the CATALOGCACHE_SZ memory heap. The regular catalog table data are in the SYSCATSPACE tablespace and its associated bufferpool.