Splitting the slots table

[Phil Longstaff]

See below prefixed by [Phil].  I've also prefixed Derek's comments with [Derek] 
where there might be confusion.

 Phil
---------
I used to be a hypochondriac AND a kleptomaniac. So I took something for it.




________________________________
From: Derek Atkins <warlord at MIT.EDU>
To: John Ralls <jralls at ceridwen.us>
Cc: Phil Longstaff <plongstaff at rogers.com>; Gnucash Devel Mailing List 
<gnucash-devel at gnucash.org>
Sent: Mon, January 3, 2011 12:00:14 PM
Subject: Re: Splitting the slots table

John Ralls <jralls at ceridwen.us> writes:

> We need to re-think KVP entirely: It doesn't match up very well with
> the relational model.

Yeah.  The KVP model works great for XML extensibility.  It does suck
for SQL extensibility.

[Derek] As we move forward I think we need to think about both methods.  We have
some requirements in that object A needs to somehow mark/tag object B
but Object B doesn't know about said tagging.  I'm not sure how you go
about doing that in a full relational database.  I suppose you could
have a "object B tag from object A" table using a foreign key, but then
you have to do a table join to get the data out,

[Phil] Which object would do the join?  For object B to load the info, it needs 
to know about object A's table.  I suppose object A could load a sub-object and 
tack it onto object B.  That might, in fact, be the best option.  Object B loads 
its stuff as normal.  Object A then loads its stuff into a struct and registers 
that struct with object B using the name "Object A's additions".  It could then 
get its stuff back, and when registering, there could be added callbacks to be 
used when object B is deleted or saved.

[Derek] and you need to make
sure that you remove the data from this new table if the object is
removed from the main table.....

[Phil] Can this not be done with the foreign key constraint using ON DELETE 
CASCADE (I think that's it)?

It all gets very complicated very quickly.

-derek
-- 
       Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
       Member, MIT Student Information Processing Board  (SIPB)
       URL: http://web.mit.edu/warlord/    PP-ASEL-IA     N1NWH
      warlord at MIT.EDU                        PGP key available