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Cardinalities in a database

How does qlikview identify the cardinality of a relationship? Does it behaves differently for different cardinalities?

6 Replies

Re: Cardinalities in a database

In principle, QlikView does not care about cardinality. Whether a link between two tables is a many-to-one or many-to-many relationship is irrelevant to QlikView. QlikView works the same way in both cases.

But having said that, there is a place where where it does matter: When showing frequency for keys in List boxes. Then QlikView tries to identify a table as the one where the key is a foreign key so that this table can be used to calculate the frequency.

HIC

Luminary
Luminary

Re: Cardinalities in a database

Hi HIC,

Is there any documentation of architecture? I wanted more understanding on Memory calculation & storage capacity.

Thanks,

DV

www.QlikShare.com

Re: Cardinalities in a database

See more on http://www.dbms2.com/2010/06/12/the-underlying-technology-of-qlikview/

About memory calculation: it is not just difficult - it is impossible.

1: The data model takes place. Proportional to number of rows x column in data table,

2: Symbol tables take place. Proportional to number of fields and number of field values (cardinality)

3: Every chart takes place. Proportional to cardinality in Dim1 x cardinality in Dim2 x cardinality in Dim3 etc, Further, if the calculation implies fields from several data tables, even more memory is needed.

Bottom line: Make test application and extrapolate.

HIC

Luminary
Luminary

Re: Cardinalities in a database

Thank you HIC. Very helpful.

Cheers - DV

http://QlikShare.com

MVP & Luminary
MVP & Luminary

Re: Cardinalities in a database

You can get details on RAM requirements for a qvw by creating a mem file (Doc Properties, General pane). Load the mem file with QV Optimizer for analysis.

You can also get memory data by using DocumentAnalyzer http://robwunderlich.com/downloads

DocAnalyzer also uses a mem file, but it creates it on the fly.

Neither of these techniques idendify the memory required for calculation, but they do give a good understanding of the RAM required for data storage and chart definitions.

-Rob

Luminary
Luminary

Re: Cardinalities in a database

Thank you Rob.