What is the meaning of this query in lucene ?
Query query =new QueryParser(Version.LATEST,"*",analyzer).parse("value");
It creates a QueryParser for the field "*" (I'm not sure if actual wildcards are allowed here - try!), using the specified analyzer. It then parses the textual query ("value") for that field. This returns a Query, which you can then use for searching through searcher.Search(query);.
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I would like to create SQL query on some text field (not keyword) for example "name" field and send that query to elastic server.
my problem is that I need to use the standard SQL language (not the MATCH and QUERY operators which are specials for elastic SQL) of text fields.
when I tried to use JDBC driver or when I tried to use high-level-java-client with LIKE operatorI got the following error
"No keyword/multi-field defined exact matches for [name]; define one or use MATCH/QUERY instead"
I also tried to use the translate API of elasticsearch- but even there I couldn't use the "LIKE" operator on text fields only on keyword fields.
does anyone have any solution for me? I want to use the LIKE operator on text fields instead of the full text operators which are unique to elastic sql.
Please check the this documentation. they have clearly mentioned in document that it is not possible.
One significant difference between LIKE/RLIKE and the full-text search
predicates is that the former act on exact fields while the latter
also work on analyzed fields. If the field used with LIKE/RLIKE
doesn’t have an exact not-normalized sub-field (of keyword type)
Elasticsearch SQL will not be able to run the query. If the field is
either exact or has an exact sub-field, it will use it as is, or it
will automatically use the exact sub-field even if it wasn’t
explicitly specified in the statement.
If you still want to used text field then you need to enabled multi-field as mentioned here. or you can try out to enable fielddata on text field but i am not sure that it will work SQL or not.
Being new to ElasticSearch, need help in my understanding.
What I read about term vs match query is that term query is used for exact match and match query is used when we are searching for a term and want result based on a relevancy score.
But if we already defined a mapping for a field as a keyword, why anyone has to decide upon between term vs match, wouldn't it be always a term query in case mapping is defined as a keyword?
What are the use cases where someone will make a match query on the keyword mapping field?
The same confusion is vice versa.
A text field will be analyzed (transformed, split) to generate N tokens, and the keyword itself will become a token with no transformations. At the end, you have N tokens referencing a document.
Then.
By doing a match query, you will treat your query as a text as well, by analyzing it before performing the matching (transforming it), and the term will not.
You can create a field with a term mapping, but then perform a match query on top of it (for example if you want to be case insensitive), and you can create a text mapping for a n-gram and perform a term query to match exactly what you're asking for.
The Wildcard Query offers a rewrite parameter to influence how Lucene calculates the relevance scores. On keyword fields this works as expected but it does not seem to work with the new wildcard field type which belongs to the keyword family. Is this an expected behavior or a bug?
As confirmed by Elastic staff, the rewrite parameter is unsupported. Unlike keyword fields, the wildcard field doesn't have a single indexed token for each term so it has no pre-built count for the document frequency of whole values. Instead it uses an ngram index which obviously has different frequencies for the multiple terms a search string can be broken down into.
In my index i have a document indexed with the field named "sn" with the value "Dorsett Shepherds Bush". When I use the match query, I can retrieve the document, but with term query I cannot retrieve the document. "sn" is a keyword field. I am doing a exact match, but still cannot get the results with the term query.
Any help would be appreciated.
Thank You.
Difference between boolean query and term query.
As far as my understanding boolean query is combination of one or more query and term query is single query to match particular field.Am in right?
Thanks in Advance..!
A bool query literally combines multiple queries of any type together with clauses such as must, must_not, and should.
A term query specifies a single field and a single term to determine if the field matches. Note that term queries are specifically for non-analyzed fields.