Increasing the SAP-NLS Performance
With the Introduction of smart data access (SDA) especially between SAP HANA and IQ, the data provisioning process can be optimized. Never the less, some additional Parameters have to be introduced on the ABAP and HANA Backend as well.
The Implementation of the SDA between SAP HANA and IQ is already discussed in the - SAP First Guidance - SAP-NLS Solution with SAP IQ | SCN This would be a mandatory task first.
A good starting point is also the following document which affects the settings for SAP-NLS in the SAP HANA database - Open ODS View on a Virtual Table | SCN and SAP BW on SAP HANA & SAP HANA Smart Data Access
Note 2128579 - Data Load into SAP IQ during Copy Phase utilizes only one server-side Thread (7.40 SP11)
With this SAP Notes two additional parameters were introduced to significantly increase the LOAD statement for writing data into SAP-NLS.
ParameterLOAD_STRIPE_SIZEsetting this parameter to a value n > 1 parallelizes the load.
Parameter LOAD_STRIPE_WITH is the parallel degree multiplied with SYBASE_IQ_BUFFER_SIZE
Parameter SYBASE_IQ_LOAD_DIRcould be changed at the database connection level (DBCO) and is by default the data directory of the SAP Instance. If you plan to load a large amount of data, please make sure that you have enough space left, or specify another directory/device.
LOAD_STRIPE_SIZE=4; LOAD_STRIPE_WIDTH=4
Furthermore there are several SAP Notes discussing the optimization:
Note 2063449 - Push down of BW OLAP functionalities to SAP HANA
Note 2165650 - FAQ: BW-Nearline-Storage mit SAP HANA Smart Data Access
Note 2100962 - FAQ: BW Near-Line Storage with HANA Smart Data Access: Query Performance
Note 2198480 - FAQ: BW Open ODS View - Query Execution
Note 2000002 - FAQ: SAP HANA SQL Optimization
Note 1987132 - SAP HANA: Parameter setting for SELECT FOR ALL ENTRIES
Note 2042333 - Deactivating the "Fast Data Access" optimization (FDA)
The following SAP Corrections are necessary (SAP BW 7.40/7.50):
Note 2099102 - SFAE implementation of LOOKUP has poor performance (7.40 SP10)
Note 2109015 - Continuation of Archiving Requests for Copy, Verification, and Deletion Phase in parallel (7.40 SP11)
Note 2130587 - SYB IQ: performance enhancement for LOAD statement (latest ASE LibDBSL 7.22, 7.42, 7.50)
Note 2198386 - BW HANA SDA: Performance Improvement for Creation of Database Statistics for Virtual Tables of Open ODS Views or NLS-Archives (7.40 SP13/7.50 SP01)
Note 2203484 - BW Near-Line Storage with HANA Smart Data Access: DTP Extraction slow (7.40 SP13/7.50 SP01)
Note 2233194 - BW Near-Line Storage with HANA Smart Data Access - PartProvider Pruning not correct (7.40 SP14)
Note 2210552 - BW Near-Line Storage with HANA Smart Data Access: Correction for Note 2203484 (7.40 SP14/7.50 SP02)
Note 2212633 - Near-Line Storage with HANA Smart Data Access doesn't read on node level (7.40 SP14/7.50 SP02)
Note 2214892 - BW HANA SDA: Process Type for creating Statistics for Virtual Tables (7.50 SP01)
Note 2202052 - BW Near-Line Storage with HANA Smart Data Access: Poor Query Performance with InfoCubes (7.40 SP13)
Queries on InfoCubes show poor performance since filter conditions are pushed as "SID-based" filters to the HANA database instead of using the "key-values" for filtering. With "SID-based" filters, the SID-table needs to be joined to the Virtual Table in order to execute the filter. This join adds complexity to the SQL-Statement which makes it more difficult to optimize the query in a federated database environment.
The following SAP Corrections are necessary aDSO Support with BW 7.50:
Note 2221933 - BW Near-Line Storage with Advanced DataStore Objects (ADSO): Query Terminations (7.50 SP02)
Note 2233471 - Query for aDSO does not read any data in near-line storage (7.50 SP02)
Note 2238384 - Advanced DataStore Object with Near-Line Storage: SQL Error with characteristic 0REQTSN (7.50 SP02)
Currently the following parameters should be changed on the SAP HANA server:
- semi_join_virtual_table_threshold
- virtual_table_format
- join_relocation
- fda_enabled
Currently the following parameters should be changed on the SAP ABAP server:
- rsdb/supports_fda_prot = 0
- rsdb/max_blocking_factor = 50
- rsdb/max_in_blocking_factor = 1024
- rsdb/prefer_union_all = 0
- rsdb/prefer_in_itab_opt = 1
- rsdb/prefer_join_with_fda = 1
With these actions you can optimize the SAP-NLS solution via SDA:
Note 2231332 - Control of Query Optimization on Near-line Storage on InfoProvider Level (7.40 SP14/7.50 SP02).
This note adds a checkbox to the "Near-line Storage" tab of the Data Archiving Process (DAP) maintenance to switch query optimization on (this is the default) or off. You must activate the DAP in order to make your setting effective. If optimization is switched on, but query optimization is not configured or not available for the Near-line Connection query access will use the non-optimized implementation via the VirtualProvider interface utilizing the Near-line Provider implementation via the standard Near-line Interface. In case Smart Data Access is configured for the Near-line Connection also the name of the HANA Virtual Table is shown.
Note 2202815 - Corrections for Column Views for Open ODS Views, Nearline Storage with SDA, Advanced DataStore Object with Dynamic Tiering (7.40 SP13/7.50 SP01).
This correction provides an optional feature that replaces the aggregation nodes on top of InfoObject tables by a projection node. This enhancement can be activated by RSADMIN Parameter RSSDA_CV_WITH_MD_PROJ
Table RSADMIN =>RSSDA_CV_WITH_MD_PROJ = X
Note 2198386 - BW HANA SDA: Performance Improvement for Creation of Database Statistics for Virtual Tables of Open ODS Views or NLS-Archives (7.40 SP13/7.50 SP01).
The Report RSSDA_CREATE_TABLE_STAT can be used to create database statistics for HANA Virtual Tables. HANA Virtual Tables are used in the context of HANA Smart Data Access. The execution time can be quite time consuming. As of HANA SP10, a new statistics type RECORD COUNT is available for virtual tables. RECORD COUNT specifies that only the number of records is computed. This type of statistics should take much less time to compute compared to the other types SIMPLE or HISTOGRAM. From query execution point of view, the HANA Query Optimizer however have less information which could lead to less optimized query execution. This type should therefore only be used in case it's too expensive to create SIMPLE or HISTOGRAM statistics.
Best Regards
Roland Kramer, PM EDW and SAP-NLS, SAP SE