Boolean Operators

About

Boolean operators allow you to apply Boolean logic to queries, requiring the presence or absence of specific terms or conditions in fields in order to match documents. The table below summarizes the Boolean operators supported by the standard query parser.

Boolean Operator
Alternative Symbol
Description
NOT ! Requires that the following term not be present.
AND && Requires both terms on either side of the Boolean operator to be present for a match.

+ Requires that the following term be present.

- Prohibits the following term (that is, matches on fields or documents that do not include that term). The - operator is functionally similar to the Boolean operator !. Because it's used by popular search engines such as Google, it may be more familiar to some user communities.
OR || Requires that either term (or both terms) be present for a match.

When specifying Boolean operators with keywords such as AND or NOT, the keywords must appear in all uppercase.

The OR operator is the default conjunction operator. This means that if there is no Boolean operator between two terms, the OR operator is used. The OR operator links two terms and finds a matching document if either of the terms exist in a document. This is equivalent to a union using sets. The symbol || can be used in place of the word OR.

For example, to search for documents that contain either "jakarta apache" or just "jakarta," use the query:

"jakarta apache" jakarta

or

"jakarta apache" OR jakarta

The Boolean Operator +

The + symbol (also known as the "required" operator) requires that the term after the + symbol exist somewhere in a field in at least one document in order for the query to return a match.

For example, to search for documents that must contain "jakarta" and that may or may not contain "lucene," use the following query:

+jakarta lucene

The Boolean Operator AND (&&)

The AND operator matches documents where both terms exist anywhere in the text of a single document. This is equivalent to an intersection using sets. The symbol && can be used in place of the word AND.

To search for documents that contain "jakarta apache" and "Apache Lucene," use either of the following queries:

"jakarta apache" AND "Apache Lucene"

"jakarta apache" && "Apache Lucene"

The Boolean Operator NOT (!)

The NOT operator excludes documents that contain the term after NOT. This is equivalent to a difference using sets. The symbol ! can be used in place of the word NOT.

The following queries search for documents that contain the phrase "jakarta apache" but do not contain the phrase "Apache Lucene":

"jakarta apache" NOT "Apache Lucene"

"jakarta apache" ! "Apache Lucene"

The Boolean Operator -

The - symbol or "prohibit" operator excludes documents that contain the term after the - symbol.

For example, to search for documents that contain "jakarta apache" but not "Apache Lucene," use the following query:

"jakarta apache" -"Apache Lucene"

Grouping Terms to Form Sub-Queries

The API supports using parentheses to group clauses to form sub-queries. This can be very useful if you want to control the Boolean logic for a query.

The query below searches for either "jakarta" or "apache" and "website":

(jakarta OR apache) AND website

This adds precision to the query, requiring that the term "website" exist, along with either term "jakarta" and "apache."