CDS, AMDP & Code Pushdown

• QuestionWhat is "The pushdown ladder"?Tap to revealAnswerPush read logic down using the most declarative layer that can express it: CDS view first, AMDP later, ABAP loops last.
• QuestionIn "The pushdown ladder", explain:Tap to revealAnswerLadder: CDS view → CDS table function + AMDP → AMDP procedure → Open SQL (joins/FAE) → ABAP loops.
• QuestionIn "The pushdown ladder", explain:Tap to revealAnswerThe most declarative layer that fits wins — it gives the optimizer the most freedom.
• QuestionIn "The pushdown ladder", explain:Tap to revealAnswerCDS views are reusable, annotatable and upgrade-stable; AMDP is opaque SQLScript.
• QuestionIn "The pushdown ladder", explain:Tap to revealAnswerDrop a rung only when the layer above cannot express the requirement.
• QuestionAnalogy for "The pushdown ladder":Tap to revealAnswerUse the highest-level tool that does the job — a spreadsheet formula before a macro, a macro before hand-copying cells.
• QuestionWhat is "CDS patterns that compress code"?Tap to revealAnswerAggregation, associations and group by turn loops-and-COLLECT into a few declarative lines — but the group by must list every non-aggregated field.
• QuestionIn "CDS patterns that compress code", explain:Tap to revealAnswerAggregation (count/sum/max/min/avg), associations, and group by compress the most code.
• QuestionIn "CDS patterns that compress code", explain:Tap to revealAnswerAssociations are declared joins, navigated by name and materialized only when used.
• QuestionIn "CDS patterns that compress code", explain:Tap to revealAnswerEvery non-aggregated select field must appear in the group by.
• QuestionIn "CDS patterns that compress code", explain:Tap to revealAnswerA missing group-by field may activate but error at runtime — expressions slip past the activator.
• QuestionAnalogy for "CDS patterns that compress code":Tap to revealAnswerIt's a pivot table: you pick the grouping column and the totals, and the engine does the counting — but you must name every column you're not summing.
• QuestionWhat is "CDS table function + AMDP"?Tap to revealAnswerWhen CDS can't express it, a table function over a read-only AMDP method can — but you must filter the client yourself with where mandt = :p_client.
• QuestionIn "CDS table function + AMDP", explain:Tap to revealAnswerUse a table function + AMDP only when CDS can't express it (recursive CTE, window functions).
• QuestionIn "CDS table function + AMDP", explain:Tap to revealAnswerAMDP read method: `by database function for hdb language sqlscript options read-only using ...`.
• QuestionIn "CDS table function + AMDP", explain:Tap to revealAnswer`options read-only` enables routing/optimization; `using` must list every referenced object.
• QuestionIn "CDS table function + AMDP", explain:Tap to revealAnswerNo implicit client — you must filter `where mandt = :p_client` explicitly.
• QuestionAnalogy for "CDS table function + AMDP":Tap to revealAnswerIt's a custom database function you write by hand: powerful, but no one auto-fills the client for you the way plain SELECT does.
• QuestionWhat is "AMDP write paths"?Tap to revealAnswerAn AMDP procedure can do set-based DML on HANA — list every table in USING, filter the client yourself, and never put options read-only on a method that writes.
• QuestionIn "AMDP write paths", explain:Tap to revealAnswerAMDP write: `by database procedure for hdb language sqlscript using ...`.
• QuestionIn "AMDP write paths", explain:Tap to revealAnswerUse set-based DML only when it beats an ABAP loop (bulk closes, mass updates).
• QuestionIn "AMDP write paths", explain:Tap to revealAnswerList ALL referenced tables in USING — a missing one errors at first execution.
• QuestionIn "AMDP write paths", explain:Tap to revealAnswerHandle the client explicitly with `where mandt = :iv_client`; there is no implicit MANDT.
• QuestionAnalogy for "AMDP write paths":Tap to revealAnswerIt's a batch SQL script: one statement updates the whole set, but you have to declare every table it touches and scope it to the right client by hand.
• QuestionWhat is "CDS access control (DCL)"?Tap to revealAnswerA DCL role puts row-level authorization inside the CDS model; #CHECK on the view requires a matching role, #NOT_REQUIRED skips it.
• QuestionIn "CDS access control (DCL)", explain:Tap to revealAnswerDCL moves row-level authorization into the model, replacing scattered AUTHORITY-CHECK.
• QuestionIn "CDS access control (DCL)", explain:Tap to revealAnswerSyntax: `define role ... { grant select on <view> where ( field ) = aspect pfcg_auth( ... ) }`.
• QuestionIn "CDS access control (DCL)", explain:Tap to revealAnswer`aspect pfcg_auth` maps a CDS field to a PFCG auth object and its fields.
• QuestionIn "CDS access control (DCL)", explain:Tap to revealAnswer`@AccessControl.authorizationCheck: #CHECK` requires a matching DCL role.
• QuestionAnalogy for "CDS access control (DCL)":Tap to revealAnswerIt's a bouncer attached to the view itself — #CHECK means there must be a guest list (the DCL role); #NOT_REQUIRED means the door is open.

1. 1Summarise the core idea

   Analyse~10 min

   In your own words, summarise the central idea of "The pushdown ladder". Aim for one paragraph, no jargon you haven't earned.

   Done when: A non-expert could read your paragraph and explain it back to you.

   Re-read the source concept

2. 2Translate it to a real situation

   Apply~15 min

   Find a real situation from your own work / life where "CDS access control (DCL)" applies. Translate the idea — describe the situation, the move you'd make, and the alternative you considered first.

   Done when: You can name a specific situation (not a hypothetical), state your move, and explain the trade-off in one paragraph.

   Re-read the source concept

3. 3Teach it back

   Evaluate~5 min

   Pick someone (a colleague, a peer, a rubber duck) and explain the section to them in under 5 minutes. Use your own example, not the one from the lesson.

   Done when: Your listener can repeat the core idea + the trade-off back to you without prompting.

Why this matters. Reading + quizzing prove recall; applying it in a real situation is the only evidence of transfer. Treat at least one of these as non-negotiable before you move on.