SAP HANA Dynamic Tiering Doubts and Questions - Brainstorming

[nicholas_chang]

Q1. Since Dynamic Tiering was claimed as Disk columnar based, appreciate if someone can shed some light on why every query runs on extended table, remote Row Scan was used instead of Column Search.

Understand that “remote” was used by SAP HANA treated extended table as virtual table.

Experiment A:

Select * from Extended Storage table and based on the visualize plan, remote row scan was used.

Experiment B:

Select specific column from Extended Storage table and based on the visualize plan, remote row scan was used as well.

Experiment C and D: Replicate experiment A and B query on HANA Columnar table. From below, we can see that Column Search was used for both queries.

Q2. In RLV enabled Extended Storage, noticed that delta is constantly high in log_es as shown below.

Since RLV is improve performance to enable write concurrently and acts like a delta store in HANA, when will the delta merge happens and will the percent used shrink down if delta merge happens?

Q3. Realize that we can enable the trace “fedtrace” for indexserver to give us how indexserver operated on esstore, is there any trace we can enable on esserver to gain more insight on how exactly esserver works?

All valuable inputs and questions are welcome and perhaps we can use this space as a central knowledge base for Dynamic Tiering.

Hopefully these questions are answered before we consider Dynamic Tiering as a solution for multi data temperature.

Cheers,

Nichoals Chang