Prefix query not analyzed

Elastic Stack Elasticsearch
1

Dear team,

I'm trying to setup a query that contain a specific prefix in a provided text (not a keyword).

PUT my-index
{
   "mappings": {
      "properties": {
         "title": {
            "type": "text",
            "analyzer": "standard",
            "fields": {
               "fr": {
                  "type": "text",
                  "analyzer": "french"
               }
            }
         }
      }
   }
}

PUT my-index/_doc/1
{
   "title": "L'Homme n'est rien d'autre que son projet."
}

GET my-index/_search
{
   "query": {
      "prefix": {
         "title.fr": "hom"
      }
   }
}

This query must return the document with id: 1 (if the prefix query was analyzed).
As documented, prefix query is not analyzed, why such behavior?

At the moment, I'm creating a custom analyzer which inherits from language analyzer (same tokenizer, char_filter and filter) to which I add a edge_gram filter.
Then I can perform a match query with this custom analyzer. Moreover I can use multi_match query.
Is this solution correct? What do you advise me?

Best regards,

Davide MARTINS

2

Welcome!

Your solution looks good to me.
I'd probably index the same text with french analyzer and your custom analyzer as a fallback.

At query time, I'd boost on the french field.
So if it matches on full terms, the score will be higher.

3

Thank you!

I'm planning to use the custom analyzer at index time and the french one at search time.

Indeed you had a good idea. I want to match first the documents with french tokens instead the ones with edge_gram.

Regarding the performances, do I need to enable specific parameters at index time and/or search time?

4

No.

BTW I wrote an example a long time ago of some combinations you could do. I hope this could help:

5

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