CODEWITHSUNDEEP
elasticsearchfull-text-search
Fabrizio Fortino
Fabrizio Fortino

Reputation: 1616

Elasticsearch: simple_query_string and multi-words synonyms

I have a field with the following search_analyzer:

"name_search_en" : {
   "filter" : [
     "english_possessive_stemmer",
     "lowercase",
     "name_synonyms_en",
     "english_stop",
     "english_stemmer",
     "asciifolding"
   ],
   "tokenizer" : "standard"
}

name_synonyms_en is a synonym_graph that looks like this

"name_synonyms_en" : {
  "type" : "synonym_graph",
   "synonyms" : [
      "beach bag => straw bag,beach bag",
      "bicycle,bike"
    ]
 }

Running the following multi_match query the synonym are correctly applied

{
  "query": {
    "multi_match": {
      "query": "beach bag",
      "auto_generate_synonyms_phrase_query": false,
      "type": "cross_fields",
      "fields": [
        "brand.en-US^1.0",
        "name.en-US^1.0"
      ]
    }
  }
}

Here is the _validate explanation output. Both beach bag and straw bag are present, as expected, in the raw query:

"explanations" : [
{
  "index" : "d7598351-311f-4844-bb91-4f26c9f538f3",
  "valid" : true,
  "explanation" : "+((((+name.en-US:straw +name.en-US:bag) (+name.en-US:beach +name.en-US:bag))) | (brand.en-US:beach brand.en-US:bag)) #DocValuesFieldExistsQuery [field=_primary_term]"
}
]

I would expect the same in the following simple_query_string

{
  "query": {
    "simple_query_string": {
      "query": "beach bag",
      "auto_generate_synonyms_phrase_query": false,
      "fields": [
        "brand.en-US^1.0",
        "name.en-US^1.0"
      ]
    }
  }
}

but the straw bag synonym is not present in the raw query

"explanations" : [
{
  "index" : "d7598351-311f-4844-bb91-4f26c9f538f3",
  "valid" : true,
  "explanation" : "+((name.en-US:beach | brand.en-US:beach)~1.0 (name.en-US:bag | brand.en-US:bag)~1.0) #DocValuesFieldExistsQuery [field=_primary_term]"
}
]

The problem seems to be related to multi-terms synonyms only. If I search for bike, the bicycle synonym is correctly present in the query

"explanations" : [
{
  "index" : "d7598351-311f-4844-bb91-4f26c9f538f3",
  "valid" : true,
  "explanation" : "+(Synonym(name.en-US:bicycl name.en-US:bike) | brand.en-US:bike)~1.0 #DocValuesFieldExistsQuery [field=_primary_term]"
}
]

Is this the expected behaviour (meaning multi terms synonyms are not supported for this query)?

Upvotes: 0

Views: 720

Answers (1)

Fabrizio Fortino
Fabrizio Fortino

Reputation: 1616

By default simple_query_string has the WHITESPACE flag enabled. The input text is tokenized. That's the reason the synonym filter doesn't handle correctly multi-words. This query disable all flags making multi-words synonyms working as expected

{
  "query": {
    "simple_query_string": {
      "query": "beach bag",
      "auto_generate_synonyms_phrase_query": false,
      "flags": "NONE", 
      "fields": [
        "brand.en-US^1.0",
        "name.en-US^1.0"
      ]
    }
  }
}

This unfortunately does not play well with minimum_should_match parameter. Full discussion and more details on this can be found here https://discuss.elastic.co/t/simple-query-string-and-multi-terms-synonyms/174780

Upvotes: 1

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