Index

Overview

Indexing, or property indexing, is a technique used to accelerate the retrieval of nodes and edges with specific properties. By avoiding full graph scans, indexes enable the database to quickly locate relevant data. This is especially advantageous when working with large graphs.

An index is created on a single property of a label.

Showing Index

Retrieve all indexes in the current graph:

GQL
SHOW INDEX

Retrieve only node or edge indexes:

GQL
SHOW NODE INDEX

GQL
SHOW EDGE INDEX

The result includes the following fields:

Field	Description
`index_name`	Index name.
`entity_type`	`NODE` or `EDGE`.
`label`	The label of the indexed property.
`property`	The indexed property name.
`prefix_length`	For string/text properties, the maximum indexed byte length. `null` if not set.
`status`	Index status: `ready`, `building`, or `error`.
`progress`	Build progress (e.g., `100%`, `50.0% (500/1000)`).
`indexed_count`	Number of entries indexed.
`total_count`	Total number of entries to index.
`error`	Error message if the build failed.

Creating Index

You can create an index using the CREATE INDEX statement. The index is built asynchronously in the background, use SHOW INDEX to check build progress.

Syntax
<create index statement> ::=
  "CREATE INDEX" <index name> "ON" < "NODE" | "EDGE" > <label>
  "(" <property name> [ "(" <length> ")" ] ")"

Details

The <index name> must be unique among nodes and among edges, but a node index and an edge index may share the same name.
For STRING or TEXT properties, you can optionally specify <length> to limit the number of characters indexed per value. If omitted, the full string is indexed. See String Length Limitation.

Create single index cBalance for the balance property of card nodes:

GQL
CREATE INDEX cBalance ON NODE card (balance)

Create single index name for the STRING-type property name of card nodes, limiting the indexed length to 10 characters:

GQL
CREATE INDEX name ON NODE card (name(10))

Create an edge index transAmount for the amount property of transfer edges:

GQL
CREATE INDEX transAmount ON EDGE transfer (amount)

Dropping Index

Dropping an index does not affect the actual property values.

GQL
DROP INDEX cBalance

You can also specify NODE or EDGE explicitly:

GQL
DROP NODE INDEX cBalance

GQL
DROP EDGE INDEX transAmountNotes

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

GQL
DROP INDEX IF EXISTS cBalance

Using Indexes

Applicable Queries

Indexes accelerate the following types of queries:

Query Type	Example
Exact match	`WHERE p.name = 'Alice'`
Range queries	`WHERE p.age > 25`, `WHERE p.age >= 20 AND p.age < 40`
Prefix search	`WHERE p.name STARTS WITH 'Al'`

Exact match:

GQL
MATCH (p:Person WHERE p.name = 'Alice')
RETURN p

Range queries:

GQL
MATCH ()-[e:Links WHERE e.weight > 5]->()
RETURN e

Prefix search:

GQL
MATCH (p:Person WHERE p.name STARTS WITH 'Al')
RETURN p.name

String Length Limitation

When a length limit N is specified for a string index, the index stores only the first N characters of each value. Queries that filter by a string longer than the limit won't match in the index.

For example, an index Username is created for the name property of user nodes with an 8-character limit:

GQL
CREATE INDEX Username ON NODE user (name(8))

The query below won't utilize the Username index because "Aventurine" (10 characters) exceeds the 8-character limit:

GQL
MATCH (n:user {name: "Aventurine"})
RETURN n

Queries with strings of 8 characters or fewer will use the index:

GQL
MATCH (n:user {name: "Kavi"})
RETURN n