Hi Yaqian Zhang,
thank you very much for the answer.
you've proposed to solutions for me as following:
1- lookup tables normalization: here i want to tell you that the lookup tables
are already normalized, but they still have about 73 attributes.
2- derived dimensions: you said that if used derived dimensions, i can create a
cube with more than 100 dimensions. my understanding to this point,
suppose i have an attribute in a dimension which i want to use as a
constraint in my query(searching, sorting, ...). There are to types of
specifying this attribute in
kylin:
1- derived: if this attribute appears in the lookup table and in the
fact table than it will appear in the cube. If it's only in the lookup table it
will not appear in the cube, therefore i can not use it as a constraint in my
query.
2- normal: it will appear in the cube.
=> so my question is: how can i specify the attributes in my dimension (lookup
table) as "derived" and be able to use them as constraints in my query, knowing
that these attributes are not in the fact table?.
thank you in advance.
best regards.
Noureddine dahmane
_______________________________________
--
Noureddine Dahmane
Software Developer
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Fax: +49 721 98993-66
E-mail: [email protected]
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Von: Yaqian Zhang [[email protected]]
Gesendet: Donnerstag, 5. Dezember 2019 12:52
An: [email protected]
Betreff: [!!Mass Mail] Re: Huge number of dimensions
Hi Noureddine:
The max physical dimension number (exclude derived column in lookup
tables) in a cube is 63; If you can normalize some dimensions to lookup tables,
with derived dimensions, you can create a cube with more than 100 dimensions.
But a cube with > 30 physical dimensions is not recommended; You even
couldn’t save that in Kylin if you don’t optimize the aggregation groups.
Please search “curse of dimensionality”.
在 2019年12月4日，22:41，Noureddine Dahmane <[email protected]<mailto:[email protected]>>
写道：
Hello,
i am trying to create a cube in kylin with the following Star schema:
- fact table: click with 32 measures
- dimension tables:
- brand : 2 columns
- campaign: 8 columns
- traffic_source: 11 columns
- shop_source: 40 columns
- traffic_source: 4 columns
- category; 8 columns
i tried to reduce the complexity of the cube based on the rules like
hierarchies, join columns and mandatory columns.
however, none of these rules can be applied to my sql statements.
Moreover, building a cube of 73 dimensions (all columns of the dimensions
tables) is not possible in KYLIN (kylin throws exception and says i should use
derived, hierarchies, and join columns to reduce the dimensions combinations).
is there any way can i do this or am i doing something wrong in kylin?
thank you in advance.
Noureddine
--
Noureddine Dahmane
Software Developer
Phone:
Fax: +49 721 98993-66
E-mail: [email protected]<mailto:[email protected]>
solute GmbH
Zeppelinstraße 15
76185 Karlsruhe
Germany
Marken der solute GmbH | brands of solute GmbH
billiger.de | Shopping.de | ka'ching Technology | Friends Communication
Geschäftsführer | Managing Director: Dr. Thilo Gans, Bernd Vermaaten
Webseite | www.solute.de
Sitz | Registered Office: Karlsruhe
Registergericht | Register Court: Amtsgericht Mannheim
Registernummer | Register No.: HRB 110579
USt-ID | VAT ID: DE234663798
Informationen zum Datenschutz | Information about privacy policy
http://solute.de/ger/datenschutz/grundsaetze-der-datenverarbeitung.php
