How to use MemorySizing.py in HANA
Is you are a HANA Administrator and have never used MemorySizing.py before , this blog will help you to get more information on the same .
1.What is the use of MemorySizing.py?
They are primarily used to Access the memory consumption of any SAP HANA system. This comprises memory usage information also on single table and attribute level . It basically helps to understand the actual memory requirement that is required for our system. It does this mostly by loading the table either fully or partially along with merging its delta if they are pending.
In HANA by default not all the column store tables or its partitions are loaded into memory unlike row store tables . Also the data stored for column store table for value LAST_ESTIMATED_MEMORY_SIZE in M_CS_TABLES will be cleared after 3 to 4 months by default. Post running this script you can observe that almost all the tables in M_CS_TABLES will have an entry against LAST_ESTIMATED_MEMORY_SIZE.
Here there are 57 tables which does not have any memory estimation .If we execute this script, all the LAST_ESTIMATED_MEMORY_SIZE gets filled up which will help us to better understand the memory usage. Additionally it also ensures a even table re-distribution if executed prior to HANA Table re-distribution.
2.Where can you find this python script ?
3.How to call it?
Output is written to memorySizing.csv in the same location.
4.What are its usage clauses ?
5.How does this help more even table re-distribution?
The script memorySizing.py(under python-support package) can be used to refresh memory statistics. This would allow to establish more accurate distribution scenario.
In some cases, there are negative numbers of MEMORY_USED in #REORG_LOCATIONS when you trigger a REORG plan which might result in mis-calculation for the table distribution, further leading to uneven table distribution. It is reported first in HANA 1.0.122.05 and It is fixed in HANA 2.0. So, running this python script would be a workaround for the issue mentioned.
6.Where to use this information or output from this file ?
-Provide information for sizing a SAP HANA system,
-Understand actual memory usage of a running SAP HANA database system
-Collect information to be used for support requests and for debugging.
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This is very useful information.