On Wed, Sep 30, 2009 at 1:04 PM, Adrian von Bidder <[email protected]>wrote:

> Heyho!
>
> Is there a tutorial on vertical partitioning?
>
> I have a table "Entry" and a table "EntryFlags" (1:1 relation from
> EntryFlags to Entry).  The idea is that while there is a large number of
> "Entry" rows only a small number has flags set (and thus needs an entry in
> EntryFlags; note that they don't need to be booleans, despite the name).
>
> So having a separate table for the EntryFlags keeps the rows of Entry
> smaller and should also speed up if I select by certain flags.
>
> How do I represent this in sqlalchemy?
>
> Obviously I can trivially do the relation stuff to get entry.flags.myflag,
> but nicer would be having the columns from the EntryFlags table appear in
> Entry as if they were inline, returning a default value where an EntryFlags
> column doesn't exist.  (Bonus for removing the EntryFlags row if all values
> are back to default ;-)
>
> Thanks in advance.
>
> -- vbi
>
>
> --
> The use of COBOL cripples the mind; its teaching should, therefore, be
> regarded as a criminal offence.
>        -- E. Dijkstra, 1975
>


Check out the "Customizing Column Properties" in the Mapper Configuation
docs:
http://www.sqlalchemy.org/docs/05/mappers.html#customizing-column-properties

If I understand correctly, this should do what you want.
(Disclaimer: haven't done it myself, YMMV)

Kevin Horn

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