Find documents with empty string value on elasticsearch

Question

I\'ve been trying to filter with elasticsearch only those documents that contains an empty string in its body. So far I\'m having no luck.

Before I go on, I should

Answer 1

in order to find the empty string of one field in your document, it's highly relevant to the field's mapping, in other word, its index/analyzer setting .

If its index is not_analyzed, which means the token is just the empty string, you can just use term query to find it, as follows:

{"from": 0, "size": 100, "query":{"term": {"name":""}}}

Otherwise, if the index setting is analyzed and I believe most analyzer will treat empty string as null value So you can use the filter to find the empty string.

{"filter": {"missing": {"existence": true, "field": "name", "null_value": true}}, "query": {"match_all": {}}}

here is the gist script you can reference: https://gist.github.com/hxuanji/35b982b86b3601cb5571

BTW, I check the commands you provided, it seems you DON'T want the empty string document. And all my above command are just to find these, so just put it into must_not part of bool query would be fine. My ES is 1.0.1.

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For ES 1.3.0, currently the gist I provided cannot find the empty string. It seems it has been reported: https://github.com/elasticsearch/elasticsearch/issues/7348 . Let's wait and see how it go.

Anyway, it also provides another command to find

{ "query": { "filtered": { "filter": { "not": { "filter": { "range": { "name": { } } } } } } } }

name is the field name to find the empty-string. I've tested it on ES 1.3.2.