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From Brian Foster <holeno...@me.com>
Subject columnbaseddatasourcecatalog
Date Thu, 23 Jun 2011 21:58:51 GMT
I'm not so sure a list of productids can be easily determined without the view ... the view
was used because this was not easy with vector elements involved ... with a query that has
a bunch of AND and OR statement you'd have some nasty join and intersect statements which
would be a nightmare to debug ... also the reason the view is not used to get the metadata
values is because the view duplicates scalar values when merged against vector values. for
example, say you have a product type which has a scalar element filename and a vector element
inputfiles. and say there is a product with filename=test.dat and inputfiles=input1.dat,input2.dat
... the view will cause a join and you will be querying a table which looks like:

productid         filename             inputfiles
1                     test.dat               input1.dat
1                     test.dat               input2.dat

hope that helps!

On Jun 23, 2011, at 2:28 PM, "Cheng, Cecilia S (388K)" <cecilia.s.cheng@jpl.nasa.gov>

> Michael -- I'm sending this to Brian's personal email address also.
> Brian -- Hope all is well. Your response will be much appreciated. Thanks!
> ------ Forwarded Message
> From: "Starch, Michael D (388L)" <Michael.D.Starch@jpl.nasa.gov>
> Reply-To: "dev@oodt.apache.org" <dev@oodt.apache.org>
> Date: Thu, 23 Jun 2011 09:36:17 -0700
> To: "dev@oodt.apache.org" <dev@oodt.apache.org>
> Cc: "Burke, John C (3880-Affiliate)" <john.c.burke@jpl.nasa.gov>
> Subject: ColumnBasedDatabase
> Brian Foster, Developers,
> This question is regarding the work I am doing to develop the column based
> database.  
> As I understood it we created views joining the three tables (Metadata,
> Reference, XREF) so that accesses to this data was at one central point,
> and the db handled the join.
> As of now the code only uses the view to get a list of distinct productid
> (which could be done easily with out the view) and where I believed the
> views would help, the tables are accessed individually in sequence.
> Is this a result of unfinished migration to using views? or is there some
> issue with using the views that I am missing.
> Was the code designed to handle multiple references per product?  As I
> understand it it is not...but I could be mistaken on this point.  If it does
> not handle them, it should, correct (for hierarchical types)?
> -Michael Starch
> ------ End of Forwarded Message

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