See more in our hbites Advanced DSO
The adso is the central object for data storage and data consolidation in the BW system.
adso can be used in various layers of the Datawarehouse based on which settings are chosen for adso.
Most often the type standard datastore object is used.
If the reporting performance is poor due to large volume or complex calculations, you can decide to use Data Mart type of DSO.
The adso consists of three core tables which are generated in the background when an ADSO is created and activated. Regardless of the type of ADSO, following three tables are always generated to support quick and flexible changes in the data model later on-
Inbound table (uncompressed fact table): /BIC/A1
table of active data (compressed fact table): /BIC/A2
Change log (not used for DataMart DSO objects): /BIC/A3
The data is initially loaded into inbound table. Reporting reads from inbound and active table using union.
Modeling objects and management of related data flow and load monitoring is completely done in the BW modeling tools (BWMT) of SAP HANA studio.
When you activate data, the data is copied to the table of active data and grouped according to the aggregation behavior.
Afterward, the data is deleted from the inbound table, the change log is not filled.
No additional keys are specified for this datastore object type, but the records are treated as if all characteristics are in the key (logical key).
Only additive deltas can be loaded. MAX, MIN, and Summation aggregations are allowed for the key figures. Therefore, the key figures cannot be overwritten.
The datastore object(advanced) can contain infoobject or fields. This allows to load data into BW without assigning infoobjects.
Characteristics that have their own master data tables connected to them are very important. A numerical SID key is generated for each characteristic value. This alias key replaces the characteristic value and allows reporting with high performance.
SID stands for Master Data ID or Surrogate ID (replacement key).
In this DataStore object, InfoObjects that are only display attributes cannot be used. Also, no fields with the following data types can be used: STRING, RAW, RAWSTRING, DF16_RAW und DF34_RAW.
The master data is adso independent and can be used by several queries from several different DataStore Objects at the same time. This concept is shown in the following graphic:
When you create Data Mart DataStore Objects, you can assign characteristics and key figures to groups.
The groups are only used as a sort criterion to provide a clearer overview when creating a query in the Query Designer.
In a Data Mart adso, all characteristics are key, and reporting is done using a union of the Inbound and Active tables. The system accesses the inbound table and the active table (using a union across both tables) in the query. In this case, you can only load additive deltas. The data is aggregated.
During the upload of data, a request is always inserted into the inbound table (new data).
Each request gets its own request ID (timestamp).
This feature enables you, for example, to delete a request from the inbound table after the upload.
However, this may result in several entries in the inbound table with the same values for all characteristics except the request ID.
This increases the size of the inbound table and decrease the performance of your queries.
During activation, these records are summarized for each request ID into the active table.
After the data has been activated, it is not possible to delete the data for a specific request ID.
Reporting on this type of DataStore Object is consistent and provides stable navigation.
A query can be run immediately after loading. You do not need to activate data beforehand. When a query is run, the active table and the inbound table are accessed.
DataStore Object can be used as source or target of transformations.
See more in our hbites Advanced DSO