Maps persistence model in DB to a consumption model exposed to clients via HTTP

HANA system is identified by a system id (SID)
HANA instances are identified by instance ids (IID)
XS engine and statistics server only exist once per system

Both the index server and XS engine can store application specific code. So what’s the difference?

Index server

•All data-intensive calculations that need to be done close to data in index server (using SQLScript, modeled views, L procedures, C++).

XS engine

•Just provides consumption model for client apps (non-performance-critical tasks, invokes views and stored procedures that are executed in the index server).
XS engine is similar to an index server without data stores and with an XS layer on top

When XS layer needs to access data:

1.Opens a local DB connection and sends an SQL statement to the local SQL proc.
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2.SQL proc determines location of data and delegates execution to index server that has the data.

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