Customer exit and optimization

Hello All,

In the Customer Exit (tcode cmod in R/3) for a specific DataSource I have an access to a table, as in this example

SELECT kostl UP TO 1 ROWS FROM cobrb INTO c_opa_6-zzbiocosts

WHERE objnr = aufk-objnr

  AND perbz = 'PER'.

ENDSELECT.

For performance reasons I want to access to this table outside of the datapackage loop and to use FOR ALL ENTRIES option.

How can I implement this possible solution?

Any help or simple example will be greatly appreciated.

Thanks in advance for your kind support.

Regards,

    Giovanni