How to match on prefix in Elasticsearch - elasticsearch

Question

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.

Answer 1

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

Answer 2

There is also a much easier way, as pointed out in elasticsearch documentation:
just use:
{
"text_phrase_prefix" : {
"fieldname" : "yourprefix"
}
}
or since 0.19.9:
{
"match_phrase_prefix" : {
"fieldname" : "yourprefix"
}
}
instead of:
{
"prefix" : {
"fieldname" : "yourprefix"
}

Answer 3

Have a look at prefix queries.
$ curl -XGET 'http://localhost:9200/index/type/_search' -d '{
"query" : {
"prefix" : { "dots" : "first.second" }
}
}'

Answer 4

You should use a commodin chars to make your query, something like this:
$ curl -XGET http://localhost:9200/myapp/index -d '{
"dots": "first.second*"
}'
more examples about the syntax at: http://lucene.apache.org/core/old_versioned_docs/versions/2_9_1/queryparsersyntax.html

Answer 5

I was looking for a similar solution - but matching only a prefix. I found #imtov's answer to get me almost there, but for one change - switching the analyzers around:
"mappings": {
"doc": {
"properties": {
"dots": {
"type": "string",
"analyzer": "keyword",
"search_analyzer": "prefix-test-analyzer"
}
}
}
}
instead of
"mappings": {
"doc": {
"properties": {
"dots": {
"type": "string",
"index_analyzer": "prefix-test-analyzer",
"search_analyzer": "keyword"
}
}
}
}
This way adding:
'{"dots": "first.second"}'
'{"dots": "first.third"}'
Will add only these full tokens, without storing first, second, third tokens.
Yet searching for either
first.second.anyotherstring
first.second
will correctly return only the first entry:
'{"dots": "first.second"}'
Not exactly what you asked for but somehow related, so I thought could help someone.