Updating with scripting

ElasticSearch allows updating a document in-place.

Updating a document via scripting reduces networking traffic (otherwise, you need to fetch the document, change the field, and send it back) and allows improving performance when you need to process a huge amount of documents.

Getting ready

You need a working ElasticSearch cluster and an index populated with the script used for facet processing, available in the online code.

How to do it...

For updating using a scripting, we will perform the following steps:

1. We'll write an update action that adds a tag value to a list of tags available in the source of a document. It should look as shown in the following code:

    curl -XPOST 'http://127.0.0.1:9200/test-index/test-type/9/_update?&pretty=true' -d '{
       "script" : "ctx._source.tag += tag",
       "params" : {
           "tag" : "cool"
       }
   }'

2. If everything is correct, the result returned by ElasticSearch...