Explain how dictionary objects import during transports or upgrade.
The Dictionary Objects including 3 level objects. The objects on ABAP Dictionary, the nametab objects, the database objects. This WIKI explains how these 3 level objects changed during DDIC (Data Dictionary) Objects import.
Scenario of DDIC Objects Import during transports
0 Before import start (general situation)
ABAP Dictionary, nametab and database objects correspond to each other.
1 DDIC objects import
A revised new version of ABAP Dictionary is imported. In this step, it is still revised, not activated. The old original 3 level objects are not affected.
2 Mass Activation
The old original ABAP Dictionary is deleted. New ABAP DIctionary is activated. New Inactive nametab is added. Old activated nametab is still in the system.
The distributor compares the definition of the new and old runtime objects. Then decides if an adaption in the database is necessary. If so, it will decide if a conversion or an execution of SQL statement is needed. The task of distribution is to generate the SQL statements for CREATE, ALTER and DROP of tables, indexes and views. Objects that cannot be changed by simple SQL statements are passed to the conversion step.
After distribution, if a conversion is necessary, the conversion program reads the new inactve nametab and compare it with old active nametab, then starts conversion. The detail scenario of conversion is here. After the conversion, the object which handled in this step is consistent again in all three levels.
5 Move nametabs (runtime objects)
The SQL statements prepared by distribution are executed, and the new definition of the runtime object is activated. Note that most inconsistencies between nametab and database object arise from this step, because rollback of DDL statements (ALTER TABLE, etc) is not possible. if the ALTER TABLE statement was successful but the following CREATE INDEX statement failed, the nametab is not moved (from inactive to active), although the table is already (partly) changed.
How every steps work
SAP Note 1368983: SE14: Unrequired conversion during activation and adjustment
SAP KBA 2048261: Inactive runtime objects in the ABAP Dictionary
SAP Note 24864: No conversion of the table BSEG
SAP Note 1283197: Cluster tables: Unnecessary conversion
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