Dear SCN readers,
I tried to find the best community for my topic (no "NLS / Archive" community exists) and finally decided this to be, for the reason of "HANA readiness"...
First of all, please apologize having not read previous topics, but since I did not find any "1893890"-related topics via the search function at all, I assume it has never been discussed?!
Probably all of you know this picture of hot, warm and cold data:
http://help.sap.com/saphelp_nw74/helpdata/en/f6/99e81daef24dfa8414b4e104fd76b7/content.htm
I heard that for migration of SAP BW 7.3x to HANA, there are several options, but best prerequisite obviously is to reduce the database size as much as possible. Independent from that, every BIA has a storage limit and therefore sooner or later NLS Archiving comes into the picture.
Since I gathered already several bad experience with archiving data from DSOs and Infocubes to Nearline Archive (NLS), I also found many topics which seem to not have been designed sophisticatedly there. I will not go into details here (if there is already a thread about the "BW developer's understanding which basic functionality a data storage should have" feel free to share the link, I'd love to contribute there.
Ok, coming to my main reason for this posting... it is this note, and the experiences recently made:
http://service.sap.com/sap/support/notes/1893890
Quote: "Solution: ... If data is read from an NLS, navigation attribute selections must be avoided as much as possible. This prevents master data from being read with some very complex SQL statement. Even after you implement the correction, avoiding navigation attribute selections may bring about a performance improvement."
@ SAP: Honestly? This is your recommended solution for the "cold" data?
Do you mean to re-model the whole BW data model to avoid using navigational attributes? Are you kidding?
This note is from February 2014. btw. Is there any update in the meanwhile, which I did not find?
In my case the data is not just "cold", it is literally "dead" data!
Yes, my main query selections are based on navigational attributes. (90% of authorization variable selections are on attributes)
And even if SAP can't imagine, there are scenarios where 5 to 25 million master data records exist for different Infoobjects.
And also Infocubes may contain a volume of 400 million records for only one year of data.
I archived about 100 Mio records and the report is not giving any result anymore - EVEN if the selected data is not in the archive!
From my point of view it is a MUST that the "data selection" recognizes if NLS is to be read or not - fast!
That means, regardless of the time characteristic used in archive and not in the query, I expect a column-optimized NLS to identify quickly that no data matches and not to cause the whole report to fail.
In that way, and this note still not resolved, it is eventually not possible to use NLS archiving to decrease the database size!
This affects the HANA migration tremendously, as I assume - right?
The only option would be selective deletion... and I guess you can imagine how happy functional departments are with that.
Would the migration to HANA revive my reports when reading archived data?
Or what is the upper limit in Mio. of records or GB until the same report fails in HANA, too?
Besides that, I would like to know the following from the participants here:
- What is your average data volume archived in "big" reporting Infoproviders (records / GB)?
- Do you have (different) performance experiences with literally "big data" volume in NLS and reporting (on attributes)?
- Is there any solution for the issues described above? Seems SAP will never provide one. :-(
FYI: The variable to read "with archive" on demand in certain queries is no solution, as the report then will never finish at all anyway.
Thanks for reading and looking forward to your comments,
Martin