Here's a rough description of how we're handling something similar: - Create a "tag query collection" consisting of the node(s) for each tag in your query (TQNodes)
- Given the tags to match, determine the "specificity" of each tag (e.g. depth in the tag hierarchy) - For the most specific tag, using relationships, traverse applicable nodes/posts to first reduce the valid set of nodes to a smaller number. We'll call this collection PostNodes - For each node/post (PostNode) in the returned list (PostNodes), get a list of tag relationships and grab the node Id's for these tags and put them in a "tag post collection" (TPNodes) - For each tag node (TPNode) in TPNodes, check for a match in the your "tag query collection" (TQNodes). If TPNode has no matches, get the parent of TPNode and re-check if it is in the TQNodes. Continue until you reach the root node in the tag hierarchy or find a match. If you reach the root node in the tag hierarchy, you do not have a match, so try the next PostNode in PostNodes. If you find a match for TPNode, try the next TPNode in TPNodes. If all the nodes in TPNodes have a match, include this PostNode in your results I'd love to know if there's a more effective way to do this as well! Rick -----Original Message----- From: user-boun...@lists.neo4j.org [mailto:user-boun...@lists.neo4j.org] On Behalf Of Alastair James Sent: Wednesday, April 07, 2010 10:54 AM To: Neo user discussions Subject: [Neo] How to efficiently query in Neo4J? Hi there... I am looking at moving a website to a model based on Neo4J, however, I am having trouble seeing how to optimise the 'main query' type for Neo4J. Briefly, the site consists of posts, each tagged with various attributes, e.g. (its a travel site) location, theme, cost etc... Also the tags are hierarchical. So, for location we have (say) 'tuscany' inside 'italy' inside 'europe'. For theme we have (say) 'cycling' inside 'activity'. I can beautifully model the parent child relationships of these 'tags' using a graph Db as objects with a 'CHILD_OF' relationship type. Then the posts go in and have related 'tags' related to them with a 'TAGGED_WITH' relationship types. Fine. However, here is the complex bit (well to me): I need to be able to find all posts tagged with a set of tags (AND operation so each post must be tagged with each tag). Whats more, these queries need to respect the parent relationships in the tags. So if I search for 'activity' in 'france' it needs to traverse the CHILD_OF relationships to find things tagged with any child of 'activity' AND any child of 'France'. It seems pretty easy to write a traversal class that would find all posts in any child of ether 'tag' node, simply follow 'CHILD_OF' and 'TAGGED_WITH' backwards and return nodes of type post. However how to do the AND bit? The only way I can see is to return both lists and union them in user code... however that seems inelegant and may not scale brilliantly. Any ideas how to optimise? Al _______________________________________________ Neo mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user _______________________________________________ Neo mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
