In Elasticsearch, a bool query is a type of query that allows you to combine multiple queries together using Boolean logic. A bool query can contain one or more sub-queries, and each sub-query can be either a full-text query, a term-level query, or another bool query. The bool query then uses Boolean operators like “must”, “should”, and “must_not” to determine how the sub-queries should be combined.
Here’s a brief overview of the Boolean operators that can be used in a bool query:
– “must”: The sub-query must match for a document to be considered a match.
– “should”: The sub-query should match, but the document can still be considered a match even if it doesn’t.
– “must_not”: The sub-query must not match for a document to be considered a match.
For example, suppose you have an index of products that includes fields for “product_name”, “description”, and “category”. You might construct a bool query that searches for products that contain the term “apple” in the “product_name” field and are in the “electronics” category. Here’s an example of what the query might look like:
{
"query": {
"bool": {
"must": [
{ "match": { "product_name": "apple" } },
{ "match": { "category": "electronics" } }
]
}
}
}
This bool query contains two sub-queries, both of which must match for a document to be considered a match. The first sub-query uses a match query to search for the term “apple” in the “product_name” field, and the second sub-query uses a match query to search for the term “electronics” in the “category” field.
By combining multiple queries together using a bool query, you can construct more complex search criteria that can help you find the documents you’re looking for more efficiently.