Indexing in Neo4j
indexing, java, neo4j
Solution
Your approach is perfectly valid. If you want to query all students of a school you can use:
Iterable<Node> pupils = index.query(schoolName + ":*");
You can also just add both fields to the index:
index.add(node, "schoolName", studentId);
index.add(node, "id", studentId);
and then query them by a combined query
Iterable<Node> pupils = index.query("schoolName:"+schoolName + " AND id:"+id);
The first one is smaller in index size but the second one is more powerful. Performance wise it won't make such a big difference (but you can test it and report back).
You could also use an structure in the graph where a school is a node and the pupils are attached to it by a `LEARNS_AT` relationship which can also have a `start` and `end` temporal property, so it is easier to model your domain. See this demo graph
Problem
I'm wonderring what's a better approach when needing to have multiple indecies based on some node type or field. For example, let's say I want to have a graph of students and want to index them by their school and id. As I understand I can have an index per school like this: ``` // add student Index<Node> index = this.graphDb.index().forNodes(schoolName); Node node = this.graphDb.createNode(); node.setProperty("id", studentId); index.add(node, "id", studentId); // get student Index<Node> index = this.graphDb.index().forNodes(schoolName); Node node = index.get("id", studentId).getSingle(); ``` I can on the other hand use one index and do something like: ``` // add student Index<Node> index = this.graphDb.index().forNodes("schools"); Node node = this.graphDb.createNode(); node.setProperty("id", studentId); index.add(node, schoolName + ":id", studentId); // get student Index<Node> index = this.graphDb.index().forNodes("schools"); Node node = index.get(schoolName + ":id", studentId).getSingle(); ``` What is a better approach? Any advantages to one over the other? Especially performance wise or storage wise, when there are a lot of nodes involved. Thanks