Using a regexp query/filter

In the previous recipes we have seen different terms queries (terms, fuzzy, and prefix), another powerful terms query is the regexp (regular expression) one.

Getting ready

You need a working ElasticSearch cluster and the data populated with the populate script.

How to do it...

For executing the regexp query/filter, we need to perform the following steps:

1. We can execute a regexp term query from command line as follows:

   curl -XPOST 'http://127.0.0.1:9200/test-index/test-type/_search' -d '{
       "query": {
           "regexp": {
               "parsedtext": "j.*",
               "flags" : "INTERSECTION|COMPLEMENT|EMPTY"
           }
       }
   }'

2. If scoring is not important, it's better to reformulate the query as a filter in the following way:

   curl -XPOST 'http://127.0.0.1:9200/test-index/test-type/_search' -d '{
       "query": {
           "filtered": {
               "filter": {
                   "regexp": {
                       "parsedtext": "j.*"
                   }
               },
               "query...