Full-text index functions¶

Use the following GQL functions with full-text indexes.

To use these functions, you need to create a full-text index first. For more information, see CREATE FULLTEXT INDEX.

ftscore()¶

Returns the score of BM25 relevance between a STRING value stored by an indexed property and a given query string.

The score is a non-negative floating-point number in the range [0, +∞). A higher score indicates greater relevance to the query string.

Null behavior: error

This function must be used together with one of the following clauses:

A WHERE clause that filters results by score (for example, score > 0).
A LIMIT clause that limits the number of results returned.

For more information, see the Examples below.

Function signature¶

ftscore(property_value_expression String, query String) -> DOUBLE

property_value_expression: The property value expression that references a STRING property of a node type or edge type. A full-text index must already be created on this property.
query: The query string against which the property value is compared to calculate the relevance score.

Examples¶

The following examples assume the full-text index ft_movie introduced in CREATE FULLTEXT INDEX is already created.

Filter by relevance score¶

'''
USE movie 
MATCH (v@Movie) 
LET score= ftscore(v.name, 'Uncle') 
FILTER WHERE score > 0 
RETURN v.name AS movie_name, score 
'''

Return:

+------------+--------------------+
| movie_name | score              |
+------------+--------------------+
| My Uncle   | 3.1877928754939955 |
+------------+--------------------+

Limit the number of results returned¶

'''
USE movie 
MATCH (v@Movie) 
LET score= ftscore(v.name, 'Star') 
RETURN v.name AS movie_name, score 
ORDER BY score ASC 
LIMIT 3
'''

Return:

+-------------------------------------+--------------------+
| movie_name                          | score              |
+-------------------------------------+--------------------+
| Star Trek III: The Search for Spock | 1.1281776534864079 |
| Star Trek: The Motion Picture       | 1.2483069947936236 |
| Star Trek: Generations              | 1.4253784613321967 |
+-------------------------------------+--------------------+