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 Indexes

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

GQL
SHOW NODE FULLTEXT

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

GQL
SHOW EDGE FULLTEXT

The information about full-text indexes is organized into the _nodeFulltext or _edgeFulltext table with the following fields:

Creating a Full-text Index

You can create a full-text index using the CREATE FULLTEXT statement. Note that each property can only have one full-text index. The full-text index creation runs as a job, you may run SHOW JOB <id?> afterward to verify the success of the creation.

System properties in Ultipa are inherently optimized for query performance and have built-in efficiencies. They do not support full-text indexing.

Syntax
<create full-text index statement> ::=
  "CREATE FULLTEXT" <full-text index name> "ON" < "NODE" | "EDGE" > <schema name> "(" <property name> ")"

Details

• The <full-text 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. Naming conventions are:
  • 2 to 64 characters.
  • Begins with a letter.
  • Allowed characters: letters (A-Z, a-z), numbers (0-9) and underscores (_).

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

GQL
CREATE FULLTEXT prodDesc on NODE product (description)

To create a full-text index named review for the property content of review edges:

GQL
CREATE FULLTEXT review on EDGE review (content)

Dropping a Full-text Index

You can drop a full-text index using the DROP NODE FULLTEXT or DROP EDGE FULLTEXT statement. Dropping a full-text index does not affect the actual property values stored in shards.

NOTE

A property with a full-text index cannot be dropped until the full-text index is deleted.

To drop the node full-text index prodDesc:

GQL
DROP NODE FULLTEXT prodDesc

To drop the edge full-text index review:

GQL
DROP EDGE FULLTEXT review

Using Full-text Indexes

To use a full-text index in the search conditions, use the syntax ~<fulltextName> CONTAINS "<keyword1> <keyword2> ...":

• The ~ symbol marks the full-text index.
• The operator CONTAINS checks if the segmented tokens in the full-text index include all the specified keywords.
• Multiple keywords should be separated by spaces. If a double quotation mark appears in a keyword, prefix it with a backslash (\) to escape.

There are two search modes for full-text indexes:

• Precise search matches exact tokens to keywords.
• Fuzzy search occurs when a keyword ends with an asterisk (*), matching tokens that begin with the keyword.

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 ~prodDesc contains "database")
RETURN n

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

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

You may revise the query as follows:

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