Full-text Index

Overview

A full-text index is a type of index specialized for efficient searching for string or text properties, especially in large text fields like descriptions, comments, or articles.

Full-text indexes work by breaking down the text into smaller segments called tokens. When a query is performed, the search engine matches specified keywords against these tokens instead of the original full text, allowing for faster retrieval of relevant results. Full-text indexes support both precise and fuzzy matches.

Showing Full-text Index

To retrieve all full-text indexes in the current graph:

GQL
SHOW FULLTEXT

To retrieve only node or edge full-text indexes:

GQL
SHOW NODE FULLTEXT

GQL
SHOW EDGE FULLTEXT

The result includes the following fields:

Field	Description
`index_name`	Full-text index name.
`entity_type`	`NODE` or `EDGE`.
`schema_name`	The label of the full-text index.
`properties`	The indexed properties.
`analyzer`	The text analyzer used.
`status`	Index status: `ready`, `loading`, or `building`.
`doc_count`	Number of documents indexed.
`progress`	Build/loading progress.

Creating Full-text Index

You can create a full-text index using the CREATE FULLTEXT statement. The index is built asynchronously, use SHOW FULLTEXT to check build progress.

Syntax
<create full-text index statement> ::=
  "CREATE FULLTEXT" <index name> "ON" < "NODE" | "EDGE" > <label>
  "(" <property name> [ { "," <property name> }... ] ")"

Details

The <index name> must be unique among nodes and among edges, but a node full-text index and an edge full-text index may share the same name.

To create a full-text index named prodDesc for the description property of product nodes:

GQL
CREATE FULLTEXT prodDesc ON NODE product (description)

To create a full-text index named reviewText for the content and excerpt properties of review edges:

GQL
CREATE FULLTEXT reviewText ON EDGE review (content, excerpt)

Dropping Full-text Index

Dropping a full-text index does not affect the actual property values.

GQL
DROP NODE FULLTEXT prodDesc

GQL
DROP EDGE FULLTEXT reviewText

Use IF EXISTS to avoid errors when the index doesn't exist:

GQL
DROP NODE FULLTEXT IF EXISTS prodDesc

Using Full-text Index

To use a full-text index in search conditions, use the syntax ~<fulltextIndexName> CONTAINS "<keywords>":

The ~ symbol marks the full-text index.
The operator CONTAINS checks if the segmented tokens in the full-text index match the query.
Results are ranked by BM25 relevance score (highest relevance first).
If a double quotation mark appears in a keyword, prefix it with a backslash (\) to escape.

Query Syntax

By default, multiple keywords separated by spaces are combined with AND (all must match). Additional operators are supported within the <keywords> string:

Operator	Syntax	Description
AND (default)	`"graph database"`	Entries whose tokens include both `graph` and `database`.
OR	`"graph OR database"`	Entries whose tokens include `graph` or `database` (or both).
NOT	`"-graph"`	Entries whose tokens do not include `graph`.
Phrase	`"\"graph database\""`	Entries whose tokens include `graph` followed immediately by `database`.
Proximity	`"\"graph database\"~5"`	Entries whose tokens include both `graph` and `database` within 5 token positions of each other.
Wildcard	`"graph*"`	Entries whose tokens start with `graph` (e.g., `graph`, `graphics`, `graphdb`).
Wildcard	`"grap?"`	Entries whose tokens match with `?` as any single character (e.g., `graph`, `grape`).
Grouped	`"(graph OR network) AND database"`	Entries matching the combined sub-expressions; parentheses control precedence.

Retrieving Nodes or Edges

To find nodes using the full-text index prodDesc where their tokens include graph and database:

GQL
MATCH (n WHERE ~prodDesc CONTAINS "graph database")
RETURN n

To find nodes using the full-text index prodDesc where their tokens include graph or database:

GQL
MATCH (n WHERE ~prodDesc CONTAINS "graph OR database")
RETURN n

To find edges using the full-text index reviewText where their tokens include graph and those start with ult:

GQL
MATCH ()-[e WHERE ~reviewText CONTAINS "graph ult*"]-()
RETURN e

Retrieving Paths

Note: Full-text indexes only apply to the first node in a path pattern when retrieving paths.

For example, this query is not supported:

GQL - Not supported
MATCH p = ()-[]-(WHERE ~prodDesc CONTAINS "graph")
RETURN p

You may revise the query as follows:

GQL
MATCH (n WHERE ~prodDesc CONTAINS "graph")
MATCH p = ()-[]-(n)
RETURN p

This query is not supported either:

GQL - Not supported
MATCH p = ()-[WHERE ~reviewText CONTAINS "ult*"]-()
RETURN p

You may revise the query as follows:

GQL
MATCH ()-[e WHERE ~reviewText CONTAINS "ult*"]-()
MATCH p = ()-[e]-()
RETURN p