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Jun 26, 2018 at 06:21 AM

How to size Hana? What is the difference between view join and materialized table join?

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Hi,

Part 1)

I'd like to know what size in GB i should make my client's HANA system.

This is a medical dataset that goes as follows.

For 1 patient he will have 2 rows in encounter table, each encounter row has 2 rows in Diagnosis table, each encounter has 100 rows in Laboratory tests and 5 rows in medications table. so for this 1 patient, with all the data joined, will produce 2x2x100x5 = 2000 rows for one patient. This hospital has 500,000 patients = 10,000,000,000 rows of data, say 50 columns wide (on average nvarchar(10) datatype).

what would be a good size HANA to run these types of queries? This is a simple join example So i want to leave headroom for more advanced queries. From my preliminary development, 128 GB is not enough.

Part 2)

I want to know why materializing tables for joins is possible when using views for joins results in Out Of Memory errors? aren't all the tables and intermediate results stored in memory anyways? what is the difference in load on the system between a table stored in memory and a view-results stored in memory?

--Matt