elasticsearch query string(full text search) which can't be searched - elasticsearch

Question

we have a document below. I can't searched with financialmarkets. but it can be searched with industry_icon_financialmarkets.png. Can anyone tell me what is the reason?
content is the text type field.
document:
{
"title":"test",
"content":"industry_icon_financialmarkets.png"
}
Query:
{
"from": 0,
"size": 2,
"query": {
"bool": {
"must": [
{
"query_string": {
"query": "\"industry_icon_financialmarkets.png\""
}
}
]
}
}
}

Answer 1

The default analyzer for text field is standard which won't break industry_icon_financialmarkets into tokens using _ as a delimiter. I would suggest you to use simple analyzer instead which will breaks text into terms whenever it encounters a character which is not a letter.
You can also add sub-field of type keyword to retain the original value.
So the mapping of the field should be:
{
"content": {
"type": "text",
"analyzer": "simple",
"fields": {
"keyword": {
"type": "keyword"
}
}
}
}

Answer 2

At the time of creating index, we should have our own mapping for each fields based on its type to get the expected result.
Mapping
PUT relevance
{"mapping":{"ID":{"type":"long"},"title":
{"type":"keyword","analyzer":"my_analyzer"},
"content":
{"type":"string","analyzer":"my_analyzer","search_analyzer":"my_analyzer"}},
"settings":
{"analysis":
{"analyzer":
{"my_analyzer":
{"tokenizer":"my_tokenizer"}},
"tokenizer":
{"my_tokenizer":
{"type":"ngram","min_gram":3,"max_gram":30,"token_chars":
["letter","digit"]
}
}
},"number_of_shards":5,"number_of_replicas":2
}
}
Then start inserting documents,
POST relevance/_doc/1
{
"name": "1elastic",
"content": "working fine" //replace special characters with space using program before inserting into ES index.
}
Query
GET relevance/_search
{"size":20,"query":{"bool":{"must":[{"match":{"content":
{"query":"fine","fuzziness":1}}}]}}}