[ic] Database design questions
Fri, 6 Apr 2001 19:27:41 -0400
Quoting Dan B (email@example.com):
> You might dig up the short thread from last year
> about Mike Heins' normalization preferences. :-)
As I am wont to, I repeat them frequently. 8-)
> As far as foreign keys, you can easily add foreign keys to your given
> database (dbconf/... files). But I imagine it's not in the distributed
> template because there is no cross-database compatibility-layer for foreign
> keys. I.e., oracle does foreign keys with command, pgsql with yet another,
> etc., ad nauseam.
> However, Mike recently made another amazing feat when he skillfully added
> the beginnings of cross-platform support for transactions in 4.7.x. Last I
> heard, it has only been tested on pgsql, but I imagine someone will do it
> on Oracle soon.
It is tested on Oracle as well. Including checking that
orders/transactions/userdb updates roll back on an error.
> Therefore, it would be considerable that someone Foreign keys could be
> built in. One problem with foreign keys is that MySQL does not support
> them (unless the new berkeleydb backend does, anyone know?). But the value
> of adding foreign keys is clearly seen by all the questions like: "Why when
> I delete from products is it still in the other tables, like pricing and
MV 4.7.x has a foreign-key extension to the data tag:
[data table=foo column=bar key=baz foreign=buz]
That ends up doing
select bar from foo where buz = 'baz'
with a virtual "LIMIT 1" and works on all database types. We have added
a DEFAULT and DEFAULT_SESSION setup so that you can do inserts with
tags like that and initialize entries that would otherwise need to be
set to honor foreign-key constraints.
And if you get stuck using the standard stuff, you can always drop into
direct DBI to do the record initialization you need.
> Foreign keys support would nip that in the bud, as well as increase
> all-around integrity of the data in the database. I don't think RH
> (Akopia) lives in a glass house either, so it would probably be fine to
> submit patches for clearly better schemas, if one were to come out of this
Next up is a built-in portable AUTO_NUMBER selector for sequences (for
dbs that support that, anyway).
Bottom line is, you can do relational stuff quite easily in Interchange.
If you really need to. 8-)
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