Re: Modeling Data for XML instead of SQL-DBMS

mAsterdam has asked me to rewrite this question in light of what I have learned and in reflecting on what my real question is. My next attempt is below. I would be grateful for any answers to the question, or additional help reforming the question if that is still required.

dawn wrote:
> If working on a software project where all data are persisted in XML
> documents and not in an SQL-DBMS, the tools would not require that the
> data model be in 1NF or the use of the SQL NULL.

Scenario: You are working on a software project where all data are persisted using database tools (using typical dictionary definitions of "database" or a definition such as "a collection of stored facts") that are not based exclusively on the relational model (SQL only as a "second language" if at all) where there are at least these two features:

1. Data are (typically) accessed using two-valued logic; "NULL" is handled logically as if it were the empty set, so that a test for NULL == NULL yields true.
2. The database tools encourage (provide functionality for) NF2 data (Non-first normal form, using traditional defs of 1NF), so there are attribute values that are lists, for example.

> How would an excellent logical data model designed for this XML
> implementation differ from the corresponding data model developed for
> an SQL-DBMS? What would be some best practices for modeling data in
> this environment?

Given a conceptual data model has been drafted for this software project, how would an excellent database design, aka implementation data model, aka database schema, differ when using these database tools from the corresponding schema developed for an SQL-DBMS?

> I'm guessing some will think that the exact same logical data model
> would be appropriate for both targets, but hopefully many will agree
> that it is unlikely that the best implemented data model would be
> identical in each environment. In that case, what would the
> differences be? What best practices would apply to data modeling for
> XML documents compared to data modeling for a SQL-DBMS?

What best practices would apply to data modeling for target database solutions compared to data modeling for a SQL-DBMS? Have any such best practices been collected to date?

Does that clarify the question? If not, I doubt my latest blog entry will clear it up, but if interested, see www.tincat-group.com/mewsings for the "Cowboys with Promiscuous Databases" entry.

Cheers! --dawn Received on Wed Nov 08 2006 - 21:59:32 CET