mutiple layer of views on core database

Database

mutiple layer of views on core database

Could any one tell if there are multiple layer of views on core database of physical layer is create , how will it impanct the performance when fetching the data by reporting tool.
The structure of the database look like

Core layer - phyical tables
Layer A on core layer - views, - One to on mapping from Core Layer.
layer B on layer A - view - one to one mapping from layer A.
Layer C on layer B - Views - some are one to one mapping from A and some are with Join and union.

Reporting tool is fetching the data from layer C .
Will it make any difference fetching data from layer C rather than layer A. and How will it impact the performance.

Thanks,
AM
1 REPLY
Enthusiast

Re: mutiple layer of views on core database

Any joins or set operations such as UNION, MINUS, EXCEPT in Layer C are going to impact performance. To what extent depends on the underlying tables that are being accessed, their data distribution, indexing, and available statistics. I would begin looking over the query plans for the problematic reports.