SAP DDIC REPLACEMENT OBJECTS Get Example source ABAP code based on a different SAP tableSAP Help
ABAP_DDIC - Replacement Objects A
transparent DDIC database table and DDIC database view can be assigned a ABAP_CDS_V2_VIEW or a ABAP_CDS_V1_VIEW as a replacement object using the name of its CDS entity. A prerequisite is that the structure type defined by the CDS view matches the structure of the DDIC database table or DDIC database view as follows: The number of components must match. It must be possible to assign a component of the CDS view to each component of the DDIC database table or DDIC database view: A client column is assigned regardless of its name. For all other components of the DDIC database table, an identically named element of the CDS view must exist. The order of the components in the DDIC database table and the CDS view does not need to match. The technical type properties built-in data type, length, and number of decimal places must match for all assigned components. The CDS view must not have any input parameters. A DDIC database view whose maintenance status is modifiable cannot have both a replacement object defined and table buffering switched on. When used as a data source of a SELECT statement in AB_SQL . This also applies to subqueries in any AB-SQL statement and to the statements OPEN CURSOR and FETCH. If table buffering is defined for the DDIC database table or the DDIC database view in question, this table buffer is bypassed. When a foreign key relationship is checked for Web Dynpros or dynpros. Writes in AB_SQL : Write access statements in AB_SQL . Use of the addition SINGLE FOR UPDATE in the statement SELECT. Writes of this type produce a syntax check warning. Use in other database objects, such as: Use as a data source of a view defined on the database. Access from database procedures or database functions. Here it is not important how the database object was created. Native views, as well as the database views defined for DDIC database views or for CDS views also do not access the replacement object. The same applies to AMDP procedures and AMDP functions and they do not access the replacement object. Even if AB_SQL is used to access a DDIC database view, a CDS view, or a CDS table function with DDIC database tables with replacement object as basis tables, the call is not redirected to the replacement object. The replacement object must be accessed directly. For DDIC database views, a new replacement object can be created that is used a replacement, without the need of modifying consumer programs. Access types other than with AB_SQL , for example: Access using IMPORT FROM DATABASE, or EXPORT TO DATABASE. Access using Native SQL ( ADBC, EXEC SQL), and AMDP. DBSQL_REDIRECT_INCONSISTENCY occurs when an AB-SQL read is performed on the DDIC database table or on the DDIC database view. global temporary tables. In customer systems, replacement objects can only be defined for user-defined database views and not for DDIC database tables. CDS roles are defined as part of the CDS access control, the associated access conditions are not evaluated when the replacement object is accessed. Latest notes: Extreme care should be taken when specifying a replacement object for a DDIC database table or a DDIC database view. Incorrect usage can cause inconsistencies. Replacement objects are mainly intended for existing aggregate tables. These are DDIC database tables that contain aggregated data from other tables. Instead of aggregating data in an ABAP program and storing it in an aggregate table, which can be exclusively accessed by reads in consumer programs, the aggregation can be performed for every read using the CDS view. This prevents redundant data from being stored. In addition, aggregation on the database can improve performance if it is necessary to read large volumes of data for aggregation in ABAP. Replacement objects allow refactoring of source code without invalidating consumer programs. A prerequisite for assigning a replacement object to an existing DDIC database table or DDIC database view is that the CDS view returns the expected data and that, apart from aggregation, only AB-SQL reads are performed on the aggregate table. Once a replacement object is defined, no further writes should be performed on an aggregate table. These writes produce a syntax check warning and are scheduled to be disallowed in an upcoming release. Make sure that, apart from the use of AB_SQL , no other type of access is performed on an aggregate table with a replacement object. In particular, the CDS view that is assigned as replacement object must not access the replaced object, because the content of replaced objects is usually no longer updated. Do not transport table content for which a replacement object is defined. Table buffering should be deactivated for an aggregate table for which a replacement object is defined to prevent buffer invalidations. In customer systems, it may be useful to define a replacement object for a user-defined DDIC database view, if a replacement object was defined for one of their basis tables at SAP. In this case, the replacement object of the view must access the replacement object of the basis table. If a DDIC database table or a DDIC database view, which a replacement object is defined for, is extended in a follow-on system, the assigned CDS view must also be extended with CDS entity extensions. DDIC projection views, DDIC maintenance views, and DDIC help views are not created on the database. Access to their basis tables is carried out on AS ABAP by using AB_SQL . If a basis table has a replacement object, reads are redirected to the replacement object. Frameworks that use AB_SQL , such as Data Browser, automatically access replacement objects if these objects are defined for a DDIC database table or a DDIC database view. Frameworks that use Native SQL or AMDP, such as the RAP query engine, do not automatically access replacement objects. The developers have to make sure that they access a replacement object rather than the replaced object. If possible, programs that previously directly accessed aggregate tables or views with aggregate tables as base tables should be modified in such a way that they access the CDS views used as replacement objects directly. However, it is not possible to simply replace the data source in the SELECT statements concerned, for example because a client-dependent CDS view has no client column and therefore the target objects used no longer match. In addition, when a CDS view is accessed directly, the CDS roles defined for this CDS view apply and might restrict the result set. Replacement objects cannot be defined for the following DDIC views: DDIC Projection Views DDIC Maintenance Views DDIC Help Views For CDS views, replacement objects are not supported at all. ABAP_EXAMPLE_ABEXA Replacement Object for Database Table
