Get Example source ABAP code based on a different SAP table
• DEFINE DEPENDENCY RULE ABAP_DDIC_STATEMENT • { } ABAP_DDIC_DEFINE_DRUL • ON ABAP_DDIC_DEFINE_DRUL • IF ABAP_DDIC_DEFINE_DRUL • THEN ABAP_DDIC_DEFINE_DRUL
ABAP_DDIC_DDL - DEFINE DEPENDENCY RULE
ABAP_SYNTAX DEFINE FILTER$| JOIN DEPENDENCY RULE drul ON dbtab $[, ...$] IF { cond_pattern } THEN { derived_cond }
What does it do? Dictionary DDL statement used to define a dependency rule. The statement has two variants:
DEFINE FILTER DEPENDENCY RULE for filter dependency rules.
DEFINE JOIN DEPENDENCY RULE for join dependency rules. The name drul of a dependency rule must comply with the naming conventions for data types and can have a maximum of 30 characters. The name is in the namespace of the DDIC data types and must match the name of the DRUL source code . After ON, the name(s) dbtab of DDIC database table(s) for which the dependency rule is defined are specified:
In the case of filter dependency rules, exactly one DDIC database table must be specified.
In the case of join dependency rules, exactly two comma-separated DDIC database tables must be specified. cond_pattern is used to specify a pattern for a relational expression after IF. In the case of reads made on the database table dbtab, the SAP HANA database optimizer searches for this pattern in the associated WHERE condition or ON condition. If the pattern is found, the optimizer uses AND to add the condition derived_cond specified after THEN to the corresponding WHERE condition or ON condition. The potential conditions are specified in the same way as in the CDS DDL or CDS DCL syntax and are described in the filter and join dependency rules.
ABAP_CAUT It cannot be guaranteed that the SAP HANA database optimizer finds the pattern cond_pattern. This is why the additional condition derived_cond must not modify the result set of the original query. It is technically possible to modify the result set with a dependency rule, but should be avoided since it produces undefined behavior in cases where the SAP HANA database optimizer finds the pattern cond_pattern in some reads but not in others.
Latest notes:
The derived condition derived_cond from a pattern cond_pattern usually defines a dependency between semantic and technical columns of a DDIC database table. When an application accesses a table with a specific selection condition for semantic columns, an additional condition for technical columns is created implicitly. In the optimization of access to deprecated data , regular date columns are the semantic columns and the temperature column is the technical column.
If multiple dependency rules are defined for a DDIC database table, AND is used to join all additional conditions and append them to the original condition.
Dependency rules can be defined for DDIC database tables only; they cannot be defined for DDIC views. The SAP HANA database optimizer evaluates all SQL accesses on DDIC database tables, including accesses with AB_SQL , AMDP, and Native SQL, plus all accesses made on views that contain the DDIC database table as a data source.
Dependency rules are not evaluated when a DDIC database table is accessed with a method other than AB_SQL , such as in calculation views.
Partners and customers cannot currently define their own dependency rules. ABAP_HINT_END
