A *term* in a purely technical sense is an entry in the inverted index.
Technically it is a very low-level entity.
For example, if you tokenized and analyzed doc1: "Dougie Turnbull" using
the English analyzer (which stems words to root forms, lowercases, etc),
you'd get an inverted index that looks somethinglike:
doug
document: 1
position 0
freq 1
turnbul
document: 1
position 1
freq 1
A "term query" therefore directly accesses terms. Its a bit of a low-level
concern. You'd have to query "doug" directly even though the original text
said "dougie".
However, loosely people use the word "search term" to mean words people
enter into a search bar.
"string" is a concept that just reflects the text being analyzed. IE
"Dougie Turnbull". This type is at the Elasticsearch level, and is a peer
for integer, floats, doubles etc. This type dicates how Elasticsearch
understands the value passed from the client and converts it to the
inverted index structure above. A string type will be analyzed, picked
apart into terms, etc based on the associated analyzer. Other types like
numeric types have other low-level magic that helps convert them to the
inverted index data structure.
Hope that helps,
-Doug
On Thu, Apr 23, 2015 at 10:42 AM, Jason Wee <peich...@gmail.com> wrote:
> Can anybody explain what is the different between term and string in
> elasticsearch context?
>
> When we index using default mapping (
> http://www.elastic.co/guide/en/elasticsearch/reference/current/indices-put-mapping.html),
> the default type is string.
>
> But when we query, we use the word term (
> http://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-term-query.html)
> instead of string?
>
> I google lucene documentation, the term is define as
>
> A query is broken up into terms and operators. There are two types of
> terms: Single Terms and Phrases. A Single Term is a single word such as
> "test" or "hello". A Phrase is a group of words surrounded by double
> quotes such as "hello dolly".
>
> but it has no mentioned on string.
>
>
> https://lucene.apache.org/core/4_10_3/queryparser/org/apache/lucene/queryparser/classic/package-summary.html#package_description
>
> Thank you.
>
> Jason
>
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--
*Doug Turnbull **| *Search Relevance Consultant | OpenSource Connections,
LLC | 240.476.9983 | http://www.opensourceconnections.com
Author: Taming Search <http://manning.com/turnbull> from Manning
Publications
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