How do I do a partial match in Elasticsearch?

问题:

I have a link like http://drive.google.com and I want to match "google" out of the link.

I have:

query: {
    bool : {
        must: {
            match: { text: 'google'} 
        }
    }
}

But this only matches if the whole text is 'google' (case insensitive, so it also matches Google or GooGlE etc). How do I match for the 'google' inside of another string?

回答1:

The point is that the ElasticSearch regex you are using requires a full string match:

Lucene’s patterns are always anchored. The pattern provided must match the entire string.

Thus, to match any character (but a newline), you can use .* pattern:

match: { text: '.*google.*'}
                ^^      ^^

One more variation is for cases when your string can have newlines: match: { text: '(.|\n)*google(.|\n)*'}. This awful (.|\n)* is a must in ElasticSearch because this regex flavor does not allow any [\s\S] workarounds, nor any DOTALL/Singleline flags. "The Lucene regular expression engine is not Perl-compatible but supports a smaller range of operators."

回答2:

use wildcard query:

'{"query":{ "wildcard": { "text.keyword" : "*google*" }}}'

回答3:

I can't find a breaking change disabling regular expressions in match, but match: { text: '.*google.*'} does not work on any of my Elasticsearch 6.2 clusters. Perhaps it is configurable?

Regexp works:

"query": {
   "regexp": { "text": ".*google.*"} 
}

回答4:

For a more generic solution you can look into using a different analyzer or defining your own. I am assuming you are using the standard analyzer which would split http://drive.google.com into the tokens "http" and "drive.google.com". This is why the search for just google isn't working because it is trying to compare it to the full "drive.google.com".

If instead you indexed your documents using the simple analyzer it would split it up into "http", "drive", "google", and "com". This will allow you to match anyone of those terms on their own.

回答5:

For both partial and full text matching ,the following worked

"query" : {
    "query_string" : {
      "query" : "*searchText*",
      "fields" : [
        "fieldName"
      ]
    }

回答6:

For partial matching you can either use prefix or match_phrase_prefix.