The flat InfoCube support on IBM i has been delivered with SAP NetWeaver BW 7.4 Support Package 13 on November 9th 2015, but we have added enhancements since then.
SAP NetWeaver BW 7.4 Support Package 15 and BW 7.5 Support Package 04 will contain quite a few improvements, and in today's blog post, I would like to point out the most important of them.
These Support Packages will be available to customers in summer 2016, but you can get the changes already now by applying the SAP notes listed below.
Flat InfoCubes always use Encoded Vector Indexes (EVIs)
Flat InfoCubes were designed specifically to take advantage of a columnar data representation in the database. On DB2 for IBM i, this is achieved by using single-column EVIs on each key column of a flat InfoCube's fact table. The standard radix index from the classic fact table is no longer necessary on flat fact tables.
One of the changes contained in SAP note 2281425 - IBM i: Index handling improved is that indexes on flat fact tables will always be EVIs, independent of whether 501572 - EVI Stage 2 Support is activated or not. Of course, it is still strongly recommended to have EVI Stage 2 Support set up, because you will need it for any remaining classic InfoCubes.
BW index limits have been raised
Flat InfoCubes on IBM i have an EVI on each key column of the fact table. The key columns comprise the column for the package dimension ID and the SID columns for each characteristic in the InfoCube.
Until now, Business Warehouse limited the number of indexes on InfoCube tables to 77. This meant that the SAP system would not create enough EVIs for flat InfoCubes with more than 77 characteristics.
In order to get optimal performance, this limit has been lifted for BW on IBM i with SAP note 2291481 - IBM i: Support more than 77 Indexes on Flat InfoCubes, so that all key columns will be provided with an EVI.
Checking size limits before converting existing InfoCubes to Flat
If you want to convert some of your larger InfoCubes into flat InfoCubes, we strongly recommend to apply the corrections from SAP note 2287899 - IBM i: Size checks before InfoCube conversion to flat before you start a conversion.
The conversion to a flat InfoCube will combine the two fact tables of the classic Infocube into one, and it will integrate the columns of the dimension tables (except for the Package dimension) into the fact table. This results in a fact table with more columns and more rows than each of the old fact tables.
The correction adds checks to the conversion tool that will make sure you don't start a conversion of an InfoCube that will fail because the new fact table exceeds one of the following size limits:
- Maximum number of InfoObjects in a flat InfoCube: 747
- Maximum number of rows in an unpartitioned table on DB2 for IBM i: 4.2 billion
- Maximum size of an unpartitioned table on DB2 for IBM i: 1.7 TB
The SAP note not only provides the code changes, it also offers suggestions regarding how to proceed if the InfoCube is too large to be converted.
