SAP Note 17947 - How can you determine the current extent size ?

Symptom:

How can you check online how much storage space is used for the allocation of an additional extent for a certain table ?

Cause and prerequisites

EXTENT and NEXT EXTENT SIZE is specified during CREATE TABLE. However, the mechanism to double the extent automatically changes the NEXT EXTENT SIZE.
If you enter "dbschema -d db_name -t tab_name -ss", only the value you have specified for CREATE TABLE is displayed as NEXT EXTENT SIZE.

Solution
The current NEXT EXTENT SIZE of a table can be determined by relocting the following commands:

- oncheck -pt db_name:tab_name
e.g. "oncheck -pt qih:atab"

If you want to change the NEXT EXTENT SIZE because of the information received here, you should execute ALTER TABLE:

- alter table tab_name modify next size anzahl_kb
e.g. "alter table atab modify next size 5000"

It is important that the output is made in pages (usually 2 or 4KB, depending on the machine) during ONCHECK whereas ALTER TABLE requires a specification in KB.