Hitchhiker's Guide to ABAP CDS since NetWeaver 7.40 SAP Inside Track 2017, Frankfurt Daniel Ridder @nielseabap

1. ABAP Core Data Services
No Pain, No Gain
Hitchhiker's Guide to ABAP CDS since NetWeaver 7.40
SAP Inside Track 2017, Frankfurt
Daniel Ridder @nielseabap

2. What’s CDS?
A beginners perspective

3. ABAP Core Data Services
Technical Description
• Technologically agnostic definition of
database views
• CDS borrowed heavily from SQL-Standard
• Supports functions of ANSI-SQL
• DDIC Object [DDLS] with can only be viewed
and edited with ADT
• Generates database native artefacts (DDL-
Statements) during activation
Context of Availability
• 1st introduction of CDS with NetWeaver 7.40
SP5 on AnyDB
• Parameter-Views came up with 7.40 SP8
(DBMS compatibility unknown at that time)
• General availability of CDS for AnyDB (incl.
Parameter-Views) since NetWeaver 7.50
! DO NO MIX UP ABAP WITH HANA CDS !
 It’s a total different technology

4. What’s the idea?
Accessing data
Programming model
Business Objects

5. Back to good software design
Data access via OpenSQL Business Objects
Performing with itabs Abstraction via API-Design

6. In the beginning the business object was created.
This has made a lot of people very angry and been widely regarded as a bad move.
Persistance
Business Object
Attributes
Locking
Links to other
Business Objects
Access via API
∙ BOPF
∙ SADL
∙ OpenSQL
• Don’t go back to the old days…
• 1st define your business
object/data model
• Make it accessible via API
• OpenSQL is still an API, but…
• do not code logic into the
statement
• use CDS Views instead
– “The truth lays inside the views”

7. Consumption and Use-Cases
• CDS may act as a read-only BO
• Is the 1st choice for analytical
processes
• Enables full code pushdown of
business logic to the database
• Can be consumed in different ways
• ABAP
• OData via Annotation or SAP Gateway
• BEx BW Tools
• …
CDS
Function
Module
SAP BW
VirtualProvider
SAP BEx Query
Business User
SAP BEx Tools
Fiori App SAP Gateway
ABAP
Floorplan Manager
No embedded BW in S/4HANA !

8. CDS – phase of activation
There is a theory which states that if ever anyone discovers exactly what CDS
activation does, it will instantly disappear and be replaced by something even more
bizarre and inexplicable…

9. Activation of a CDS Parameter-View
HDB on NetWeaver 7.50 SP3
• There is no specification of SQL
database views supporting
parameters
• Due to this a parameter view
becomes a complex native artifact
• A function object with a table as a
result set has to be created
• On HDB the definition of the
function is generated in SQLScript

10. There is a theory which states that if ever anyone discovers exactly
what CDS activation does, it will instantly disappear and be replaced by
something even more bizarre and inexplicable.
- There is another theory which states
that this has already happened.
Activation of a CDS Parameter-View
Oracle on NetWeaver 7.40 SP11

11. DROP TABLE "Z_DATATABLE“
error in DDL statement for "Z_DATATABLE“
SQL-error "-478-[IBM][CLI Driver][DB2] ALTER,
DROP, OR REVOKE AFFECTING OBJECT TYPE FUNCTION
CANNOT BE PROCESSED BECAUSE OBJECT
SAPR3.Z_DATAVIEW OF TYPE FUNCTION IS DEPENDENT ON
IT" in DDL statement for "Z_DATATABLE"
--------------- DB-ROLLBACK() ---------------
error in DDL, nametab for "Z_DATATABLE" not
activated
…after activation on Oracle:
Here comes DB2 on zOS
Problem description
• Extending/Modifying a database table during
SAINT yields to an upgrade error during
activation phase
DBMS- specific Lifecycle management
Trans.
Table
Trans.
Table
CDS View
W. Parameters
<dependency>
Unhandled
dependencies between
native artifacts!
“[IBM][CLI Driver][DB2] SQL0101N The statement is too
long or too complex.”

12. The walk of pain
Avoid ABAP CDS in an heterogeneous DBMS landscape

13. CDS on NetWeaver 7.40
“The Walk of pain”
Dec 2015 Jun 2016 Nov 2016
2331160 - Renaming of CDS artifacts in
customer systems
https://launchpad.support.sap.com/#/notes/23
31160
Still 3x open incidents in system
upgrade process / SPAM breaks
• DB2/zOS
• DB2
• Upgrade-Performance
SAINT/SPAM breaks during activation phase
• incorrect order of activation
• wrong quantity of activation
• problems with cyclic dependencies
• problems after renaming of views
• SELECT *
Problems while upgrading to
NetWeaver 7.50:
• undocumented change of CDS
specification (order of key attributes)
SAINT/SPAM breaks during activation phase
• incorrect order of activation
Development Track

14. Small selection of “hitting” notes
• Note 2240326 - Cycle problems during activation of CDS views
• cycles are subject to “some restrictions”  No documentation at that time
• Notes 2295005 - Data element change for table does not result in reactivation of all DDL sources during transport
2381956 - Inconsistent 'SELECT *' CDS views
2274996 - Problems with deletion of table or view fields with select * dependencies
• „Select-Star is for looser“
• Note 2239157 - Support of database features
• „Official“ GA of CDS Views with parameters in NetWeaver 7.50 on AnyDB  What about the introduction in 7.40 SP8?
• Note 2331160 - Renaming of CDS artifacts in customer systems
• CDS Views could be renamed  DDLS, CDS-Name, DDIC-Name (DDIC-Rename is always prohibited)
• Note 2387971 - Incompatible ABAP changes from Release 7.40 to 7.50
• Since NetWeaver 7.50 all key attributes must be located together at the start of SELECT

15. ABAP Core Data Services is a key technology
CDS goes further
• CDS let you define a VDM – virtual data model
under S/4HANA (BO 1st)
• HDB supports the definition of ABAP CDS table
functions
• Which solves a lack of AMDPs
• CDS Test Double Framework
• The upcoming S/4HANA programming model
depends heavily on CDS Views
• The draft concept combines CDS and BOPF for
transactional Fiori-Applications and is triggered by CDS
annotations
Recommendations using CDS
Recommendations based on our experiences:
• CDS > NetWeaver 7.40 > AnyDB
• Do not built huge view hierarchies (< 5 level, not more
than 10 views)
• Do not use parameters!
• Avoid cycles in associations
• Perform activation tests on each dbms target platform
• CDS > NetWeaver 7.50 > AnyDB
• We will see…
• CDS > NetWeaver 7.50 > HANA
• No restrictions
• CDS > NetWeaver 7.51 S/4HANA
• rocks

16. So Long, and Thanks for All the Fish
Daniel Ridder
@nielseabap