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February 24, 2021Elasticsearch offers 2 different contexts on how you have query or filter documents in an index – Query context and Filter context.
Query context
- In the query context, a query clause answers the question “How well does this document match this query clause?”
- In query context, Elasticsearch tries to determine whether the document matches the search text and how well it matches.
- Will provide a relevance _score in the output which tells you the relevance of the match result.
- Results are not cached
Eg. book_description field contains the word amazingly realistic.
Filter context
- In a filter context, a query clause answers the question “Does this document match this query clause?”
- Filter context evaluates to a simple “Yes” or “No”
- Doesn’t provide you with relevance _score
- Frequently used filters will be cached automatically by Elasticsearch, to speed up performance.
Eg. book_status field is published
Example
curl -X GET "localhost:9200/book/_search?pretty" -H 'Content-Type: application/json' -d'
{
"query": {
"bool": {
"must": [
{ "match": { "book_description": "amazingly realistic" }}
],
"filter": [
{ "term": { "book_status": "published" }}
]
}
}
}
'
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