All this talk of parent and child nodes makes me wonder if my SQLAlchemy-based persistence add-on (pNetworkX) to the NetworkX graph package might be of interest. You could use pNetworkX with your chosen database to maintain a directed graph that represents the parent-child relationships between your XML nodes, and use a separate table to contain per-node attributes.
http://foss.eepatents.com/pNetworkX/ Best regards, Ed Suominen Luís Bruno wrote: > Florian Boesch wrote: >> Table('children', engine, >> Column('children_id', Integer, Sequence('children_seq'), >> primary_key=True), >> Column('tag_node_id', Integer, ForeignKey('tag_node.id'), >> nullable=False), >> Column('node_id', Integer, ForeignKey('node.id'), nullable=False), >> Column('ordering', Integer, nullable=False), >> ) > > I'd prefer to have a list of parent nodes; one of the properties of > these trees is that each node has one parent only (except root, which > has none): > > CREATE TABLE parents ( > node_id INTEGER NOT NULL REFERENCES node(id), > parent_id INTEGER NOT NULL REFERENCES node(id), > ordering INTEGER NOT NULL, > > PRIMARY KEY (node_id, parent_id), > UNIQUE (node_id, ordering) -- probably screwed the syntax here > ); > > This way, you can select all of a node's children (by checking if it's > referenced in the parent_id column) or select all parents (by getting > the list of parent's for a node). > > Thank you once again Mike, for providing that article; I still can't > wrap my brain around it properly, but this model seems quite nice. > ------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid0709&bid&3057&dat1642 _______________________________________________ Sqlalchemy-users mailing list Sqlalchemy-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/sqlalchemy-users
