{"id":28019,"date":"2015-10-21T11:00:05","date_gmt":"2015-10-21T08:00:05","guid":{"rendered":"http:\/\/examples.javacodegeeks.com\/?p=28019"},"modified":"2020-08-08T16:11:46","modified_gmt":"2020-08-08T13:11:46","slug":"solr-join-example","status":"publish","type":"post","link":"https:\/\/examples.javacodegeeks.com\/java-development\/enterprise-java\/apache-solr\/solr-join-example\/","title":{"rendered":"Solr Join Example"},"content":{"rendered":"

In this example of Solr Join, we will discuss about how to implement join between documents in Apache Solr. We will show you how to implement the Join Query Parser plugin specified by {!join}. The join is used in Solr documents where de-normalizing the data is time consuming or costly.<\/p>\n

To demonstrate the Solr Join\u00a0usage, we will create a core in Solr using basic configuration and index sample files shipped along with Solr installation.<\/p>\n

Our preferred environment for this example is solr-5.0.0. Before you begin the Solr installation make sure you have JDK installed and Java_Home is set appropriately.<\/p>\n<\/p>\n

1. Install Apache Solr<\/h2>\n

To begin with, let’s download the latest version of Apache Solr from the following location:<\/p>\n

http:\/\/lucene.apache.org\/solr\/downloads.html<\/code><\/p>\n

Apache\u00a0Solr has gone through various changes from 4.x.x to 5.0.0, so if you have a different version of Solr you need to download the 5.x.x. version to follow this example.<\/p>\n

Once the Solr zip file is downloaded, unzip it into a folder. The extracted folder will look like the below:<\/p>\n

\"solr_folder\"<\/a>
Solr folders<\/figcaption><\/figure><\/p>\n

The bin<\/code> folder contains the scripts to start and stop the server. The example<\/code> folder contains few example files. We will be using one of them to demonstrate how Solr indexes the data. The server<\/code> folder contains the logs<\/code> folder where all the Solr logs are written. It will be helpful to check the logs for any error during indexing. The solr<\/code> folder under server holds different collection or core. The configuration and data for each of the core\/ collection\u00a0are stored in the respective core\/ collection\u00a0folder.<\/p>\n

Apache Solr comes with an inbuilt Jetty server. But before we start the solr instance we must validate the JAVA_HOME is set on the machine.<\/p>\n

We can start the server using the command line script. Lets go\u00a0to the bin directory from the command prompt and issue the following command:<\/p>\n

solr start<\/code><\/p>\n

This will start the Solr server under the default port\u00a08983.<\/p>\n

We can now open the following URL in the browser and\u00a0validate that our Solr instance is running. The specifics of solr admin tool is beyond the scope of the example.<\/p>\n

http:\/\/localhost:8983\/solr\/<\/code><\/p>\n

\"Solr<\/a>
Solr admin console<\/figcaption><\/figure><\/p>\n

2. Configuring Apache Solr<\/h2>\n

In this section,\u00a0we will show you how to configure the core\/collection for a solr instance and how to define the fields. Apache Solr ships with an option called Schemaless mode. This option allow users to construct effective schema without manually editing the schema file. But for this example we will use the Schema configuration for understanding the internals of the Solr.<\/p>\n

2.1 Creating a\u00a0Core<\/h3>\n

When the Solr server is started\u00a0in Standalone mode, the configuration is called core and when it is started\u00a0in SolrCloud mode, the configuration is called Collection. In this example we will discuss about the standalone server and core. We will park the SolrCloud discussion for later time.<\/p>\n

First, we need to create a Core\u00a0for indexing the data.\u00a0The Solr create command has the following options:<\/p>\n