[elasticsearch] Install and access head plugin in elasticsearch

There are many customized plugins that comes with elasticsearch. In this article we will see how to install and then how to use the head plugin with elasticsearch.


Here are few steps that we need to follow:

Step1:
To install head plugin from site use following command:

bin/plugin --install mobz/elasticsearch-head

 You will be able to install the plugin using above only when you have internet connectivity and your firewall alows you to download and install

Else you can manually download the elasticsearch-head.zip plugin from https://github.com/mobz/

Run the following command

bin/plugin --url file:///d:\elasticsearch-head.zip --install mobz/elasticsearch-head

Step 2:

Restart the elasticsearch instance and you will be able to access it as

http://localhost:9200/_plugin/head/

[SOLR] How to join fl default parameters and request parameters?

If I have set of fields, specified in fl of some SearchRequestHandler configuration in xml, then fl specified in query request parameter will override fl specified in SearchRequestHandler configuration in xml.

I want that SOLR to do Join of fl parameters from query and from SearchRequestHandler instead of overriding it.

For example:

If in query I have fl=field1,field2 and in SearchRequestHandler configuration; I have fl=field3,field1 then join of these two as fl=field1,field2,field3. 

For this issue you can use following solution:

You can use <lst name="appends"> in your requestHandler definition to make Solr append the values to the query instead of replacing them. Since fl can be added several times to the same request, this works as you're extending the list of fields to retrieve.

<requestHandler name="/select" class="solr.SearchHandler">

    <lst name="appends">

        <str name="fl">cat</str>

    </lst>

</requestHandler>

This solution will help you when you have too many fl fields that needs to defined and few of them changes as per the query.

[SOLR] Implementing Facet with multiple categories along with their count

How can we facet on more than two categories ( ‘project’ and ‘type’ as discussed below) and at the same time get the combination facets and their count.

Example : http://search-lucene.com/

When you open URL, http://search-lucene.com/?q=facets you can see the facets on right hand side as 'Project','type','date','author' and their corresponding values with count in brackets.

For instance, let’s say you select 'solr(32857)' under 'Project' facet, still we can see other values under 'Project' facet like ElasticSearch etc. along with their respective count. 

Further when we Select 'mail # user(23138)' under “type” section , again we can see other values under “type” section with their corresponding count in brackets and their corresponding values in “Project” facet gets changed accordingly (namely the count ). 

Observe how solr(32857) changed to Solr (22969) post selection of mail # user along with the other values of ‘Project’ (like ElasticSearch etc.) and ‘type’ (issue, javadoc etc.,) with a change in their count values.

To achieve similar functionality you can use following solution:

Use Tagging and excluding Filters: http://wiki.apache.org/solr/SimpleFacetParameters#Tagging_and_excluding_Filters

select?q=solr%20facets&fq={!tag=projectTag}Project:"solr"&fq={!tag=typeTag}type:"mail # user"&facet=true&facet.field={!ex=projectTag}project&facet.field={!ex=typeTag}type&wt=json&indent=true

Using the above solution I am able to implement the faceting solution mentioned in above website using SOLR.

Hope this is useful information for your all!!!!