large db question about no joins

Aaron Brady castironpi at
Sat Apr 18 03:39:39 CEST 2009

On Apr 17, 3:16 pm, "Martin P. Hellwig" <martin.hell... at>
> Daniel Fetchinson wrote:
> <cut>
> > In an relational database setting you would have a table for artists,
> > a table for cd's and a table for songs and a table for comments where
> > people can comment on songs. All of this with obvious foreign keys.
> > Now you want to display on your website the total number of cd's, the
> > total number of songs and the total number of comments because that
> > looks very cool on top of every page: 1242342 cd's and 134242342342
> > songs and 284284728347284728 comments!
> > Okay, so you need to issue a query with joins in your relational db.
> > Or in another query, you want to select all comments of an artist,
> > meaning all comments that were comments on a song belonging to cd's of
> > a given artist. This would also involve joins.
> > How would I do these queries if I can't have joins or in other words
> > how would I lay out my data storage?
> > Thanks by the way for your help and replies,
> > Daniel
> What actually is happening here is that feature x which is usually in an
> abstraction layer (like a RDBM) is not available to you. Which means you
> have to write code which does the same but on your side of the code.
> I played a bit around with the GAE some time ago and designed the
> storage of all data in an sort of EAV model
> (
> The abstraction layer had all my meta code, counting stuff up was a
> matter of creating a list of id's from one section and with that list
> selecting the appropriate records on the other section, then count up
> the number of results or use the result again, it is very likely you
> have to do quite a lot of queries before you get the result.
> So in other words, just lay out the data which makes the most sense to
> you, the pain of recreating SQL like logic is there no matter what
> layout you choose.
> --
> mph

Instead of creating a new table, just create an iterator that returns
successive entries in it.  Just don't change the size of either table
during iteration.

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