Elastic Search with phonetic search

Question

Im trying to get Elastic Search making a phonetic search in a list of cities. My goal is to find matching results even if the user uses an incorrect spelling.

I've done the following steps:

Remove domain
```
curl -X DELETE "localhost:9200/city/"
```

Create new domain

curl -X PUT "localhost:9200/city/?pretty" -H 'Content-Type: application/json' -d'                                                      
{
  "settings": {
    "index": {
      "analysis": {
        "analyzer": {
          "my_analyzer": {
            "tokenizer": "standard",
            "filter": [
              "lowercase",
              "my_metaphone"
            ]
          }
        },
        "filter": {
          "my_metaphone": {
            "type": "phonetic",
            "encoder": "metaphone",
            "replace": true
          }
        }
      }
    }
  },
  "mappings": {
    "properties": {
      "name": {
        "type": "text",
        "analyzer": "my_analyzer"
      }
    }
  }
}'

Fill some sample data

curl -X PUT "localhost:9200/city/_doc/1?pretty" -H 'Content-Type: application/json' -d'
{
   "name":"Mayrhofen"
}
'

curl -X PUT "localhost:9200/city/_doc/2?pretty" -H 'Content-Type: application/json' -d'
{
   "name":"Ischgl"
}
'

curl -X PUT "localhost:9200/city/_doc/3?pretty" -H 'Content-Type: application/json' -d'
{
   "name":"Saalbach"
}
'

Search in the cities - here I get an result

curl -X GET ""localhost:9200/city/_search?pretty" -H 'Content-Type: application/json' -d'
{
   "query":{
      "query_string":{
         "query":"Mayrhofen" 
      }
   }
}
'

I tried the query with Mayerhofen and expected the same result as using Mayrhofen. The same issue with Ischgl and Ichgl or Saalbach and Salbach.

Where's my error? Is something mssing?

score 1 · Accepted Answer · answered Jul 14 '20 at 09:08

Problem is that you are using wrong encoder. metaphone cannot match those.

What you need to use is double_metaphone for your inputs. It's based on phonetic algorithm implementation. I would suggest you to understand your data and algorithm to ensure whether the phonetic algorithm is best fit for your purpose.

Mapping:

{
      "analysis": {
        "analyzer": {
          "double_meta_true_analyzer": {
            "tokenizer": "standard",
            "filter": [
              "lowercase",
              "true_doublemetaphone"
            ]
          }
        },
        "filter": {
          "true_doublemetaphone": {
            "type": "phonetic",
            "encoder": "double_metaphone",
            "replace": true
          }
        }
      }
    }

It matches the docs.

Why metaphone is not matching:

GET http://localhost:9200/city2/_analyze
{
   "field":"meta_true",
   "text":"Mayrhofen"
}

yields

{
    "tokens": [
        {
            "token": "MRHF",
            "start_offset": 0,
            "end_offset": 9,
            "type": "<ALPHANUM>",
            "position": 0
        }
    ]
}

And analysing below

{
   "field":"meta_true",
   "text":"Mayerhofen"
}

yields

{
    "tokens": [
        {
            "token": "MYRH",
            "start_offset": 0,
            "end_offset": 10,
            "type": "<ALPHANUM>",
            "position": 0
        }
    ]
}

Double_Metaphone works the below way:

GET
{
   "field":"doublemeta_true",
   "text":"Mayerhofen"
}

And

{
   "field":"doublemeta_true",
   "text":"Mayerhofen"
}

and

{
   "field":"doublemeta_true",
   "text":"Mayrhofen"
}

yields

{
    "tokens": [
        {
            "token": "MRFN",
            "start_offset": 0,
            "end_offset": 10,
            "type": "<ALPHANUM>",
            "position": 0
        }
    ]
}

Thank you for your help... stupidly every example I found using phoentic search was using `metaphone` encoder. — Marco, Jul 15 '20 at 05:44
Hi @Gibbs: Is there a way to get the "correct" search phrase, like google does: "Did you mean: mayrhofen" when I look for "Maierhofen"? — Marco, Jul 17 '20 at 07:09
You need to use phrase `suggester` and handle it in your code. — Gibbs, Jul 17 '20 at 08:04
Are there any special installations or configurations needed? — Marco, Jul 17 '20 at 09:43

Elastic Search with phonetic search

1 Answers1