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 peichieh@gmail.com wrote:
Can anybody explain what is the different between term and string in
elasticsearch context?
When we index using default mapping (
Update mapping API | Elasticsearch Guide [8.11] | Elastic),
the default type is string.
But when we query, we use the word term (
Term query | Elasticsearch Guide [8.11] | Elastic)
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.
org.apache.lucene.queryparser.classic (Lucene 4.10.3 API)
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
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