[Mondrian] <join>, <Query> and <view> for snowflake schemas (Selina Tech)

Stefano Celati stefano.celati at bnova.it
Mon Mar 21 09:41:48 EDT 2016


Hi,
Way 1 is the best, IMHO, because the "joined outer table" will be used 
only when you're asking an element from that table (or for some caching 
stuff).
Way 2 & Way 3 will generate the underlying SQL for EVERY user query, so 
it's to be used only when you want to "materialize" something you don't 
have in your DB (a concatenation of fields or an outer-joined relationship).

HTH
Stefano

Il 19/03/2016 17:00, mondrian-request at pentaho.org ha scritto:
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>     1. <join>,<Query> and <view> for snowflake schemas (Selina Tech)
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> ----------------------------------------------------------------------
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> Message: 1
> Date: Fri, 18 Mar 2016 16:32:49 -0700
> From: Selina Tech <swucareer99 at gmail.com>
> Subject: [Mondrian] <join>,<Query> and <view> for snowflake schemas
> To: Mondrian developer mailing list <mondrian at pentaho.org>
> Message-ID:
> 	<CAOpZfza7hL66Q3psz-p9q-5AYpB7WiJoCpdkw+uYPZHSvuE_Mg at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Dear All:
>
>      When I study the Mondrian schema. I think we have three different ways
> for the Dimension of snowflake schema.
>
> Way 1:  Use <Join> as the example at
> http://mondrian.pentaho.com/head/documentation/schema.php#Star_schemas
>
> Way 2: Use <Query> to define a ?table?, and use this ?table? for Dimension
> table
>
> Way 3. Use <View>  to define a view ?table? by <SQL> and use this ?table?
> for Dimension table
>
>       Is any one of them wrong? if they are right, how could I choose one of
> them? How is the different on performance?  when we use <view>, is this
> <view> will generated in memory, disk or database? what happen if the
> result of view is huge on size?
>
>
> Your any help is highly appreciated.
>
> Sincerely,
> Selina
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Stefano Celati
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