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Former Member
Nov 01, 2016 at 07:33 PM

revisitied - are there two levels, L1 and L2 of delta stores

195 Views Last edit Nov 04, 2016 at 12:51 PM 3 rev

hello all

i have to re-address this question because the original has been archived (https://archive.sap.com/discussions/thread/3928885)

in short about 2 delta store areas, do they exist

L1 - row based, uncompressed

L2 - column based, dictionary compressed (unsorted)

here was the short answer "Sorry, but the details on the delta store implementation are not externally documented, so I cannot go into more detail here.

As mentioned before, the understanding of the L1 delta concept is correct - but it's not active in any productive SAP HANA code."

now, few months after, i read something, albeit written in 2013, but by an important person, who states that for high speed event recording, this type of data does actually write to row store delta (very short term), and is merged into column delta before the main column memory.

anyone have any new information on this, as it is nice to be clear when talking to customers.

in the event of no responses, i can only conclude, the delta L1 row based does exist, and the delta L2 - is column based. They both work together.