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https://github.com/litegraphdb/litegraph

Lightweight graph database with relational and vector support built using Sqlite, designed to power knowledge and artificial intelligence persistence and retrieval.
https://github.com/litegraphdb/litegraph

ai arangodb database gexf graph llm neo4j neptune tigergraph titan vector vector-database

Last synced: 3 months ago
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Lightweight graph database with relational and vector support built using Sqlite, designed to power knowledge and artificial intelligence persistence and retrieval.

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README 

          



# LiteGraph



[![NuGet Version](https://img.shields.io/nuget/v/LiteGraph.svg?style=flat)](https://www.nuget.org/packages/LiteGraph/) [![NuGet](https://img.shields.io/nuget/dt/LiteGraph.svg)](https://www.nuget.org/packages/LiteGraph) 



LiteGraph is a property graph database with support for graph relationships, tags, labels, metadata, data, and vectors.  LiteGraph is intended to be a unified database for providing persistence and retrieval for knowledge and artificial intelligence applications.



LiteGraph can be run in-process (using `LiteGraphClient`) or as a standalone RESTful server (using `LiteGraph.Server`).



## New in v4.0.x



- Major internal refactor for both the graph repository base and the client class

- Separation of responsibilities; graph repository base owns primitives, client class owns validation and cross-cutting

- Consistency in interface API names and behaviors

- Consistency in passing of query parameters such as skip to implementations and primitives

- Consolidation of create, update, and delete actions within a single transaction

- Batch APIs for creation and deletion of labels, tags, vectors, edges, and nodes

- Enumeration APIs

- Statistics APIs

- Simple database caching to offload existence validation for tenants, graphs, nodes, and edges

- In-memory operation with controlled flushing to disk

- Dependency updates and bug fixes

- Minor Postman fixes



## Bugs, Feedback, or Enhancement Requests



Please feel free to start an issue or a discussion!



## Simple Example, Embedded 



Embedding LiteGraph into your application is simple and requires no configuration of users or credentials.  Refer to the ```Test``` project for a full example.



```csharp

using LiteGraph;



LiteGraphClient graph = new LiteGraphClient(new SqliteRepository("litegraph.db"));

graph.InitializeRepository();



// Create a tenant

TenantMetadata tenant = graph.CreateTenant(new TenantMetadata { Name = "My tenant" });



// Create a graph

Graph graph = graph.CreateGraph(new Graph { TenantGUID = tenant.GUID, Name = "This is my graph!" });



// Create nodes

Node node1 = graph.CreateNode(new Node { TenantGUID = tenant.GUID, GraphGUID = graph.GUID, Name = "node1" });

Node node2 = graph.CreateNode(new Node { TenantGUID = tenant.GUID, GraphGUID = graph.GUID, Name = "node2" });

Node node3 = graph.CreateNode(new Node { TenantGUID = tenant.GUID, GraphGUID = graph.GUID, Name = "node3" });



// Create edges

Edge edge1 = graph.CreateEdge(new Edge { TenantGUID = tenant.GUID, GraphGUID = graph.GUID, From = node1.GUID, To = node2.GUID, Name = "Node 1 to node 2" });

Edge edge2 = graph.CreateEdge(new Edge { TenantGUID = tenant.GUID, GraphGUID = graph.GUID, From = node2.GUID, To = node3.GUID, Name = "Node 2 to node 3" });



// Find routes

foreach (RouteDetail route in graph.GetRoutes(

  SearchTypeEnum.DepthFirstSearch,

  tenant.GUID,

  graph.GUID,

  node1.GUID,

  node2.GUID))

{

  Console.WriteLine(...);

}



// Export to GEXF file

graph.ExportGraphToGexfFile(tenant.GUID, graph.GUID, "mygraph.gexf");

```



## Simple Example, In-Memory



LiteGraph can be configured to run in-memory, with a specified database filename.  If the database exists, it will be fully loaded into memory, and then **must** later be `Flush()`ed out to disk when done.  If the database does not exist, it will be created.



```csharp

using LiteGraph;



LiteGraphClient graph = new LiteGraphClient(new SqliteRepository("litegraph.db", true)); // true to run in-memory

graph.InitializeRepository();



// Create a tenant

TenantMetadata tenant = graph.CreateTenant(new TenantMetadata { Name = "My tenant" });



// Create a graph

Graph graph = graph.CreateGraph(new Graph { TenantGUID = tenant.GUID, Name = "This is my graph!" });



// Create nodes

Node node1 = graph.CreateNode(new Node { TenantGUID = tenant.GUID, GraphGUID = graph.GUID, Name = "node1" });

Node node2 = graph.CreateNode(new Node { TenantGUID = tenant.GUID, GraphGUID = graph.GUID, Name = "node2" });

Node node3 = graph.CreateNode(new Node { TenantGUID = tenant.GUID, GraphGUID = graph.GUID, Name = "node3" });



// Create edges

Edge edge1 = graph.CreateEdge(new Edge { TenantGUID = tenant.GUID, GraphGUID = graph.GUID, From = node1.GUID, To = node2.GUID, Name = "Node 1 to node 2" });

Edge edge2 = graph.CreateEdge(new Edge { TenantGUID = tenant.GUID, GraphGUID = graph.GUID, From = node2.GUID, To = node3.GUID, Name = "Node 2 to node 3" });



// Flush to disk

graph.Flush();

```



## Working with Object Labels, Tags, and Data



The `Labels` property is a `List` allowing you to attach labels to any `Graph`, `Node`, or `Edge`, i.e. `[ "mylabel" ]`.



The `Tags` property is a `NameValueCollection` allowing you to attach key-value pairs to any `Graph`, `Node`, or `Edge`, i.e. `{ "foo": "bar" }`.



The `Data` property is an `object` and can be attached to any `Graph`, `Node`, or `Edge`.  `Data` supports any object serializable to JSON.  This value is retrieved when reading or searching objects, and filters can be created to retrieve only objects that have matches based on elements in the object stored in `Data`.  Refer to [ExpressionTree](https://github.com/jchristn/ExpressionTree/) for information on how to craft expressions.



The `Vectors` property can be attached to any `Graph`, `Node`, or `Edge` object, and is a `List`.  The embeddings within can be used for a variety of different vector searches (such as `CosineSimilarity`).



All of these properties can be used in conjunction with one another when filtering for retrieval.



### Storing and Searching Labels



```csharp

List labels = new List 

{

  "test",

  "label1"

};



graph.CreateNode(new Node { TenantGUID = tenant.GUID, Name = "Joel", Labels = labels });



foreach (Node node in graph.ReadNodes(tenant.GUID, graph.GUID, labels))

{

  Console.WriteLine(...);

}

```



### Storing and Searching Tags



```csharp

NameValueCollection nvc = new NameValueCollection();

nvc.Add("key", "value");



graph.CreateNode(new Node { TenantGUID = tenant.GUID, Name = "Joel", Tags = nvc });



foreach (Node node in graph.ReadNodes(tenant.GUID, graph.GUID, null, nvc))

{

  Console.WriteLine(...);

}

```



### Storing and Searching Data



```csharp

using ExpressionTree;



class Person 

{

  public string Name { get; set; } = null;

  public int Age { get; set; } = 0;

  public string City { get; set; } = "San Jose";

}



Person person1 = new Person { Name = "Joel", Age = 47, City = "San Jose" };

graph.CreateNode(new Node { TenantGUID = tenant.GUID, GraphGUID = graph.GUID, Name = "Joel", Data = person1 });



Expr expr = new Expr 

{

  "Left": "City",

  "Operator": "Equals",

  "Right": "San Jose"

};



foreach (Node node in graph.ReadNodes(tenant.GUID, graph.GUID, null, expr))

{

  Console.WriteLine(...);

}

```



### Storing and Searching Vectors



It is important to note that vectors have a dimensionality (number of array elements) and vector searches are only performed against graphs, nodes, and edges where the attached vector objects have a dimensionality consistent with the input.



Further, it is strongly recommended that you make extensive use of labels, tags, and expressions (data filters) when performing a vector search to reduce the number of records against which score, distance, or inner product calculations are performed. 



```csharp

using ExpressionTree;



class Person 

{

  public string Name { get; set; } = null;

  public int Age { get; set; } = 0;

  public string City { get; set; } = "San Jose";

}



Person person1 = new Person { Name = "Joel", Age = 47, City = "San Jose" };



VectorMetadata vectors = new VectorMetadata 

{

  Model = "testmodel",

  Dimensionality = 3,

  Content = "testcontent",

  Vectors = new List { 0.1f, 0.2f, 0.3f }

};



graph.CreateNode(new Node { Name = "Joel", Data = person1, Vectors = new List { vectors } });



foreach (VectorSearchResult result in graph.SearchVectors(

  VectorSearchDomainEnum.Node,

  VectorSearchTypeEnum.CosineSimilarity,

  new List { 0.1f, 0.2f, 0.3f },

  tenant.GUID,

  graph.GUID,

  null,  // labels

  null,  // tags

  null,  // filter

))

{

  Console.WriteLine("Node " + result.Node.GUID + " score " + result.Score);

}

```



### Enumeration Ordering



A variety of `EnumerationOrderEnum` options are available when enumerating objects.



- `CreatedAscending` - sort results in ascending order by creation timestamp

- `CreatedDescending` - sort results in descending order by creation timestamp

- `NameAscending` - sort results in ascending order by name

- `NameDescending` - sort results in descending order by name

- `GuidAscending` - sort results in ascending order by GUID

- `GuidDescending` - sort results in descending order by GUID

- `CostAscending` - for edges only, sort results in ascending order by cost

- `CostDescending` - for edges only, sort results in descending order by cost

- `MostConnected` - for nodes only, sort results in descending order by total edge count

- `LeastConnected` - for nodes only, sort results in ascending order by total edge count



To enumerate, use the enumeration API for the resource you wish.



```csharp

EnumerationQuery query = new EnumerationQuery

{

  Ordering = EnumerationOrderEnum.CreatedDescending,

  IncludeData = true,

  IncludeSubordinates = true,

  MaxResults = 5,

  ContinuationToken = null,         // set to the continuation token from the last results to paginate

  Labels = new List,        // labels on which to match

  Tags = new NameValueCollection(), // tags on which to match

  Expr = null,                      // expression on which to match from data property

};



EnumerationResult result = graph.Node.Enumerate(query);

// returns

{

    "Success": true,

    "Timestamp": {

        "Start": "2025-06-22T01:17:42.984885Z",

        "End": "2025-06-22T01:17:43.066948Z",

        "TotalMs": 82.06,

        "Messages": {}

    },

    "MaxResults": 5,

    "ContinuationToken": "ca10f6ca-f4c2-4040-adfe-9de3a81b9f55",

    "EndOfResults": false,    // whether or not the end of the results has been reached

    "TotalRecords": 17,       // total number of matching records

    "RecordsRemaining": 12,   // records remaining should you enumerate again

    "Objects": [

        {

            "TenantGUID": "00000000-0000-0000-0000-000000000000",

            "GUID": "ebefc55b-6f74-4997-8c87-e95e40cb83d3",

            "GraphGUID": "00000000-0000-0000-0000-000000000000",

            "Name": "Active Directory",

            "CreatedUtc": "2025-06-21T05:23:14.100128Z",

            "LastUpdateUtc": "2025-06-21T05:23:14.100128Z",

            "Labels": [],

            "Tags": {},

            "Data": {

                "Name": "Active Directory"

            },

            "Vectors": []

        }, ...

    ]

}

```



### Gathering Statistics



Statistics are available both at the tenant level and at the graph level.



```csharp

Dictionary allTenantsStats = graph.Tenant.GetStatistics();

TenantStatistics tenantStatistics = graph.Tenant.GetStatistics(myTenantGuid);



Dictionary allGraphStatistics = graph.Graph.GetStatistics(myTenantGuid);

GraphStatistics graphStatistics = graph.Graph.GetStatistics(myTenantGuid, myGraphGuid);

```



## REST API



LiteGraph includes a project called `LiteGraph.Server` which allows you to deploy a RESTful front-end for LiteGraph.  Refer to `REST_API.md` and also the Postman collection in the root of this repository for details.  By default, LiteGraph.Server listens on `http://localhost:8701` and is only accessible to `localhost`.  Modify the `litegraph.json` file to change settings including hostname and port.



Listening on a specific hostname should not require elevated privileges.  However, listening on any hostname (i.e. using `*` or `0.0.0.0` will require elevated privileges).



```csharp

$ cd LiteGraph.Server/bin/Debug/net8.0

$ dotnet LiteGraph.Server.dll



  _ _ _                          _

 | (_) |_ ___ __ _ _ _ __ _ _ __| |_

 | | |  _/ -_) _` | '_/ _` | '_ \ ' \

 |_|_|\__\___\__, |_| \__,_| .__/_||_|

             |___/         |_|



 LiteGraph Server

 (c)2025 Joel Christner



Using settings file './litegraph.json'

Settings file './litegraph.json' does not exist, creating

Initializing logging

| syslog://127.0.0.1:514

2025-01-27 22:09:08 joel-laptop Debug [LiteGraphServer] logging initialized

Creating default records in database litegraph.db

| Created tenant     : 00000000-0000-0000-0000-000000000000

| Created user       : 00000000-0000-0000-0000-000000000000 email: default@user.com pass: password

| Created credential : 00000000-0000-0000-0000-000000000000 bearer token: default

| Created graph      : 00000000-0000-0000-0000-000000000000 Default graph

Finished creating default records

2025-01-27 22:09:09 joel-laptop Debug [ServiceHandler] initialized service handler

2025-01-27 22:09:09 joel-laptop Info [RestServiceHandler] starting REST server on http://localhost:8701/

2025-01-27 22:09:09 joel-laptop Alert [RestServiceHandler]



NOTICE

------

LiteGraph is configured to listen on localhost and will not be externally accessible.

Modify ./litegraph.json to change the REST listener hostname to make externally accessible.



2025-01-27 22:09:09 joel-laptop Info [LiteGraphServer] started at 01/27/2025 10:09:09 PM using process ID 56556

```



## Running in Docker



A Docker image is available in [Docker Hub](https://hub.docker.com/r/jchristn/litegraph) under `jchristn/litegraph`.  Use the Docker Compose start (`compose-up.sh` and `compose-up.bat`) and stop (`compose-down.sh` and `compose-down.bat`) scripts in the `Docker` directory if you wish to run within Docker Compose.  Ensure that you have a valid database file (e.g. `litegraph.db`) and configuration file (e.g. `litegraph.json`) exposed into your container.



## Version History



Please refer to ```CHANGELOG.md``` for version history.