How to match on prefix in Elasticsearch

elasticsearch

Solution

Elasticsearch has Path Hierarchy Tokenizer that was created exactly for such use case. Here is an example of how to set it for your index:

# Create a new index with custom path_hierarchy analyzer 
# See http://www.elasticsearch.org/guide/reference/index-modules/analysis/pathhierarchy-tokenizer.html
curl -XPUT "localhost:9200/prefix-test" -d '{
    "settings": {
        "analysis": {
            "analyzer": {
                "prefix-test-analyzer": {
                    "type": "custom",
                    "tokenizer": "prefix-test-tokenizer"
                }
            },
            "tokenizer": {
                "prefix-test-tokenizer": {
                    "type": "path_hierarchy",
                    "delimiter": "."
                }
            }
        }
    },
    "mappings": {
        "doc": {
            "properties": {
                "dots": {
                    "type": "string",
                    "analyzer": "prefix-test-analyzer",
                    //"index_analyzer": "prefix-test-analyzer", //deprecated
                    "search_analyzer": "keyword"
                }
            }
        }
    }
}'
echo
# Put some test data
curl -XPUT "localhost:9200/prefix-test/doc/1" -d '{"dots": "first.second.third"}'
curl -XPUT "localhost:9200/prefix-test/doc/2" -d '{"dots": "first.second.foo-bar"}'
curl -XPUT "localhost:9200/prefix-test/doc/3" -d '{"dots": "first.baz.something"}'
curl -XPOST "localhost:9200/prefix-test/_refresh"
echo
# Test searches. 
curl -XPOST "localhost:9200/prefix-test/doc/_search?pretty=true" -d '{
    "query": {
        "term": {
            "dots": "first"
        }
    }
}'
echo
curl -XPOST "localhost:9200/prefix-test/doc/_search?pretty=true" -d '{
    "query": {
        "term": {
            "dots": "first.second"
        }
    }
}'
echo
curl -XPOST "localhost:9200/prefix-test/doc/_search?pretty=true" -d '{
    "query": {
        "term": {
            "dots": "first.second.foo-bar"
        }
    }
}'
echo
curl -XPOST "localhost:9200/prefix-test/doc/_search?pretty=true&q=dots:first.second"
echo

Problem

let's say that in my elasticsearch index I have a field called "dots" which will contain a string of punctuation separated words (e.g. "first.second.third"). I need to search for e.g. "first.second" and then get all entries whose "dots" field contains a string being exactly "first.second" or starting with "first.second.". I have a problem understanding how the text querying works, at least I have not been able to create a query which does the job.

Original source