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Full-Text-Indexing (FTS) in Neo4j 2.0

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Full-Text-Indexing (FTS) in Neo4j 2.0

· Java Zone
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What every Java engineer should know about microservices: Reactive Microservices Architecture.  Brought to you in partnership with Lightbend.

With Neo4j 2.0, we got automatic schema indexes based on labels and properties for exact lookups of nodes on property values.

Fulltext and other indexes (spatial, range) are on the roadmap but not addressed yet.

For fulltext indexes you still have to use legacy indexes.

As you probably don’t want to add nodes to an index manually, the existing “auto-index” mechanism should be a good fit.

To use that automatic index you have to configure the auto-index upfront to be a fulltext index and then secondly enable it in your settings.

Setup Node Auto-Index as Fulltext-Index

To configure the auto-index as fulltext index for your Neo4j Server use:

POST http://localhost:7474/db/data/index/node/
Accept: application/json; charset=UTF-8
Content-Type: application/json
{
  "name" : "node_auto_index",
  "config" : {
    "type" : "fulltext",
    "provider" : "lucene"
  }
}

You should get a response like this:

201: Created
Content-Type: application/json; charset=UTF-8
Location: http://localhost:7474/db/data/index/node/node_auto_index/
{
  "template" : "http://localhost:7474/db/data/index/node/node_auto_index/{key}/{value}",
  "type" : "fulltext",
  "provider" : "lucene"
}

Enable Node Auto-Index for certain properties

Configure and enable the auto-index in your conf/neo4j-server.properties. You have to enable the auto-index and also list the properties to be indexed upfront, before you insert any data.

node_auto_indexing=true
node_keys_indexable=title,description

If you configure it after the fact you have to re-set the properties with a cypher statement like this:

MATCH (n)
WHERE has(n.title)
SET n.title=n.title

If you already have many nodes in your database you have to batch it manually to cater for the transaction size limits, like this (increase SKIP by 50000 from 0 to until the query returns zero):

MATCH (n)
WHERE has(n.title)
SKIP 150000 LIMIT 50000
SET n.title=n.title
RETURN COUNT(*)

Using the Fulltext Auto-Index

You can use the fulltext auto-index by using a START-clause in Cypher, you can pass in any kind of lucene query syntax there.

START movie=node:node_auto_index("title:matr*")
MATCH (movie:Movie)<-[r:RATED]-(user)
WHERE r.rating > 4
RETURN movie, count(*) AS number, avg(r.rating) AS ratings
ORDER BY ratings desc, number desc

Java-API

You can also set it up programmatically in the Java API like this:

db.index().forNodes( "node_auto_index",
        MapUtil.stringMap( IndexManager.PROVIDER, "lucene", "type", "fulltext" ) );

And pass your configuration to your EmbeddedGraphDatabase

GraphDatatabaseService db = new GraphDatabaseFactory().newEmbeddedGraphDatabaseBuilder(DB_PATH)
   .setConfig("node_auto_indexing","true").setConfig("node_keys_indexable","title,description")
   .newGraphDatabase();

And then use it like this:

IndexHits<Node> nodes = db.index().forNodes( "node_auto_index").query("title:matr*");
for (Node n : nodes) {
   // do something
}
// remember to close indexhits if you don't exhaust it
nodes.close();

Custom Configuration

You can also configure additional specifics for the fulltext index, like a custom
analyzer class, just pass it to the config.

{
  "name" : "node_auto_index",
  "config" : {
    "type" : "fulltext",
    "provider" : "lucene"
    "to_lower_case" : true,
    "analyzer" : "com.example.indexing.MyAnalyzer"
  }
}

Microservices for Java, explained. Revitalize your legacy systems (and your career) with Reactive Microservices Architecture, a free O'Reilly book. Brought to you in partnership with Lightbend.

Topics:
java ,nosql ,architecture ,tips and tricks ,neo4j ,full-text-indexing ,tools & methods

Published at DZone with permission of Michael Hunger, DZone MVB. See the original article here.

Opinions expressed by DZone contributors are their own.

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