Anyone? On Jan 22, 3:29 pm, Boz <[email protected]> wrote: > Whoops, the key columns in the mapping should be NodeId, not ChildId. > Sorry > > Boz > > On Jan 22, 2:44 pm, Boz <[email protected]> wrote: > > > Hi, > > > I'm an nHibernate novice at the moment, and have been advised to post > > here from the Fluent group to see if you guys can suggest an efficient > > mapping or some SQL for a multi parent relationship. Then the Fluent > > guys can help me translate any suggestions you have into Fluent code > > (if appropriate). > > > The scenario... > > > I have a legacy database with two tables which allow nodes to map to > > other nodes in a hierarchy. Simplified, > > the tables are: > > > NodesTable (NodeId, Name) > > ParentsTable (NodeId, ParentId) > > > This can modelled in a single entity and its map (please excuse the > > map being Fluent nHibernate code!): > > public class Node > > { > > public virtual decimal NodeId { get; set; } > > public virtual string Name { get; set; } > > public virtual IList<Node> Parents { get; set; } > > public virtual IList<Node> Children { get; set; } > > } > > > public class NodeMap : ClassMap<Node> > > { > > HasManyToMany(x => x.Parents) > > .ParentKeyColumn("ChildID") > > .ChildKeyColumn("ParentID") > > .Inverse(); > > HasManyToMany(x => x.Children) > > .ParentKeyColumn("ParentID") > > .ChildKeyColumn("ChildID"); > > } > > > This maps fine, and the collections all contain the correct parents > > and children > > > The application requires that the "downward" (child) relationships for > > each node are shown in a tree view (and nodes with many parents are > > indicated as "shared" with other nodes in the tree). I'm retrieving > > this initial "tree" > > with: > > > public IList<Node> GetNodes() > > { > > var query = from nodes in Session.Linq<Node>() > > orderby nodes.Name ascending > > select nodes; > > return query.ToList(); > > } > > > Now to the problem.... > > > The tree view shows the nodes correctly, but it is *very* slow even > > with only 50 or so records in each table. When configuring the maps > > Parents and Children maps to eagerly load you can see a just how bad > > the performance is - many queries are executed in both directions > > (each node's parents and each node's children) > > > Perhaps this can be solved by enhancing the session query? Or by > > manipulating each map's FetchType? Being an nHibernate novice, I'd > > really appreciate any guidance you guys have. > > > Boz
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