Code Pushdown
What it is
The principle of doing data-intensive work in the database (via CDS/AMDP/open SQL) instead of pulling rows into ABAP and looping. 'Let HANA do the heavy lifting close to the data.'
Why it matters for Clean Core
It's the performance model S/4HANA assumes and a recurring theme in custom-code remediation: the biggest classic-ABAP performance sins are nested SELECTs and ABAP-side aggregation that should have been one CDS query.
Common pitfall
Migrating code to ABAP Cloud syntactically but keeping the loop-and-SELECT shape. Cloud-clean and performant are different goals — push the set logic down as part of the rewrite, not as a later 'optimisation'.