[ZODB-Dev] How do you handle changes to BTree key values?

[Christian Robottom Reis]

On Tue, 9 Oct 2001, Michel Pelletier wrote:

> Probably. ;) ZODB really just provides you with an "object universe"
> that is persistent over time.  This persistence of your data is realy
> the only thing it has in common with a relational database.  The data

Just to reiterate here, this is something I've had to wrap my brain around
with the ZODB. It is a persistence mechanism, but by default it includes
no retreival mechanism or indexing.

This means that _you_ are responsible for telling the ZODB how to store
information based on how you plan on retrieving it. You need a specific
storage and retrieval plan, though you can accomodate for changes later by
adding other indexes.

> In a relational database, you need to use keys, tables, rows etc
> because the data model constrains you to that.  For certain problem

The relational model also provides you with an interesting mechanism for
retrieving your persisted information, where it can correlate with similar
data in other relations and columns. This is a very important aspect of an
RDBMS that hasn't been hashed out enough here: when you abandon it, you
are not only abandoning persistence but retrieval and indexing (optimized
retrieval, IOW).

When you choose to use ZODB, you agree to cook your own. If this is
acceptable, as it is to me, the unbelievably simple to use persistence
mechanism can really shine.

Take care,
--
Christian Reis, Senior Engineer, Async Open Source, Brazil.
http://async.com.br/~kiko/ | [+55 16] 272 3330 | NMFL