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Former Member
Oct 23, 2012 at 03:01 PM

Is really all data in memory?

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After doing some tests ( final results will be made available at this other discussion http://scn.sap.com/thread/3252533 ) i was wondering what is going on.

I found this on wikipedia:

The row store is optimized for concurrent WRITE and READ operations. It keeps all index structures in-memory rather than persisting them on disk. It uses a technology that is optimized for concurrency and scalability in multi-core systems. Typically, Metadata or rarely accessed data is stored in a row-oriented format.( http://en.wikipedia.org/wiki/SAP_HANA#Column_and_row_store )

And from HANA's reference we can read:

Syntax

 LOAD <table_name> {DELTA | ALL | (<column_name>, ...)} 

Description

The LOAD statement loads the column store table data to memory explicitely instead of on first access.

( http://help.sap.com/hana/html/sql_load.html )

The LOAD statement is explicitly for column store, if you try to run it for a row store table it give's you an error.

I serched a little bit on HANA's sites and couldn't find an explicit statement so can anyone confirm:

SAP HANA works with full data in memory only for column store, when working with row store only indexing structures are held in memory. Is that so?