topic Re: Loading from SQL Database Views in QlikView

Loading from SQL Database Views

Wed, 30 Dec 2015 16:03:13 GMT

Hi ,

Looks like when loading directly from the Database Views(which is created using the same query in qvs) is taking longer time compared to loading the same using a QVS which query against the DB.

Is that how it works?

Re: Loading from SQL Database Views

Clever_Anjos — Wed, 30 Dec 2015 16:05:42 GMT

It would supposed to be the same time.

It depends on

Which RDBMS
Which indexes are beeing used
How many records are beeing retrieved
How often the database statistics are beein collected
How your view was created (Materialized views speed performance)

Re: Loading from SQL Database Views

Peter_Cammaert — Wed, 30 Dec 2015 16:06:07 GMT

You mean it takes longer to load data from a Database View than it takes to load the same data from the constituent Database Tables?

That's normal. The Database engine has to populate the View before it can start transmitting rows. This is a set-up cost (delay). It has no such problem when reading directly from tables where the optimizer can start transmitting rows almost immediately..

Re: Loading from SQL Database Views

maxgro — Wed, 30 Dec 2015 16:41:10 GMT

A view (not materialized) is a stored queryn (where stored is the definition of the query, not the result), usually it takes the same time to run

- a query

and

- the same query stored as a view

Re: Loading from SQL Database Views

Anonymous — Wed, 30 Dec 2015 17:46:04 GMT

While loading from a view does take longer, the dynamic nature of a view insures that you are getting the most current version of the data. We are migrating all of our views ( 100's ) to static tables in a data warehouse. Our data requirements do not necessitate more than day old data, so we elected the performance improvement of pulling directly from tables.