Username search in Elasticsearch - elasticsearch

Question

I want to implement a simple username search within Elasticsearch. I don't want weighted username searches yet, so I would expect it wouldn't be to hard to find resources on how do this. But in the end, I came across NGrams and lot of outdated Elasticsearch tutorials and I completely lost track on the best practice on how to do this.
This is now my setup, but it is really bad because it matches so much unrelated usernames:
{
"settings": {
"index" : {
"max_ngram_diff": "11"
},
"analysis": {
"analyzer": {
"username_analyzer": {
"tokenizer": "username_tokenizer",
"filter": [
"lowercase"
]
}
},
"tokenizer": {
"username_tokenizer": {
"type": "ngram",
"min_gram": "1",
"max_gram": "12"
}
}
}
},
"mappings": {
"properties": {
"_all" : { "enabled" : false },
"username": {
"type": "text",
"analyzer": "username_analyzer"
}
}
}
}
I am using the newest Elasticsearch and I just want to query similar/exact usernames. I have a user db and users should be able to search for eachother, nothing to fancy.

Answer 1

If you want to search for exact usernames, then you can use the term query
Term query returns documents that contain an exact term in a provided field. If you have not defined any explicit index mapping, then you need to add .keyword to the field. This uses the keyword analyzer instead of the standard analyzer.
There is no need to use an n-gram tokenizer if you want to search for the exact term.
Adding a working example with index data, index mapping, search query, and search result
Index Mapping:
{
"mappings": {
"properties": {
"username": {
"type": "text",
"fields": {
"keyword": {
"type": "keyword"
}
}
}
}
}
}
Index Data:
{
"username": "Jack"
}
{
"username": "John"
}
Search Query:
{
"query": {
"term": {
"username.keyword": "Jack"
}
}
}
Search Result:
"hits": [
{
"_index": "68844541",
"_type": "_doc",
"_id": "1",
"_score": 0.2876821,
"_source": {
"username": "Jack"
}
}
]
Edit 1:
To match for similar terms, you can use the fuzziness parameter along with the match query
{
"query": {
"match": {
"username": {
"query": "someting",
"fuzziness":"auto"
}
}
}
}
Search Result will be
"hits": [
{
"_index": "68844541",
"_type": "_doc",
"_id": "3",
"_score": 0.6065038,
"_source": {
"username": "something"
}
}
]