Hi
We found a situation with the new ontology hierarchy that needs a common reflexion between us.
Explanation:
Hierarchies in Dédalo are connected with children data. It was implemented in v4 because this model is fast when you want open terms in the tree. With children model, Dédalo store data in component_relation_children and parent terms are calculated, so parent data doesn't exist into database, you can handle it but in reality, parent data is transformed into the equivalent children data.
This model is ok for the thesaurus, and it works perfectly by years, until now, and for the new Ontology editor. Ontology editor uses the same model that thesaurus model, storing data into the children component and parent is calculated. It works except for local ontologies (ontologies created by specific installation that are not common and is created with its own tld), in those cases the children model has limitations because this ontology nodes needs to be defined in its parents as children of they, therefore, children model implies that we need to know this local terms and pointed it with general nodes. And we want a model that general terms will be independent of local nodes.
Therefore, we are thinking to change the hierarchy model to store parents data and the children data will be calculated. But this model has implications about the current thesaurus tree.
- First, the main term defined into hierarchy section as top term can not be used as parent, because it has not parent (is the top node), and it needs to define the children into the hierarchy (it use the hierarchy45 and hierarchy59).
In this case, a solution could be add a top term into the hierarchy as toponymy has:
Spain (hierarchy term not used as descriptor)
└──→ Spain (thesaurus node)
└──→ Andalucía (thesaurus node)
└──→ Aragón (thesaurus node)
And eliminate the hierarchy node in the tree, in this way:
Spain (thesaurus node)
└──⦿ Andalucía (thesaurus node)
└──⦿ Aragón (thesaurus node)
But in other cases you could have multiple terms in hierarchy as first node:
Thematic (hierarchy term not used as descriptor)
└──→ Culture (thesaurus node)
└──→ Education (thesaurus node)
In those cases, we are planning to create a term at top as toponym has:
Thematic (hierarchy term not used as descriptor)
└──→ Thematic (thesaurus node)
└──→ Culture (thesaurus node)
└──→ Education (thesaurus node)
And point current top nodes to this new top node with parent link, and remove as I explained, so the final tree will be:
Thematic (thesaurus node)
└──⦿ Culture (thesaurus node)
└──⦿ Education (thesaurus node)
Without the hierarchy node.
Second, the use of the parent model is a different model and the current Time Machine data has the historical data of children component, and we are thinking that is not necessary to move it to the parent component. Because it will be funcional in children, if you want to revert the children will be interpreted as parent data and it will work. So, the question is: current children Time Machine needs to be converted to parent Time Machine?
Third, the parent model has a speed impact when you navigate from the tree, and how deal with searches... is OK for you?
If we have consensus about the change it will be implemented in v6.5.0.
Best
