Graph Management

The GQLDB Java driver provides methods to create, delete, list, and manage graphs in the database.

Graph Types

GQLDB supports three graph types defined in the GraphType enum:

Java
import com.gqldb.types.GraphType;

GraphType.OPEN      // Schema-less graph (default)
GraphType.CLOSED    // Schema-enforced graph
GraphType.ONTOLOGY  // Ontology-enabled graph

Creating Graphs

createGraph()

Create a new graph in the database:

Java
import com.gqldb.*;
import com.gqldb.types.GraphType;

public void createGraphExample(GqldbClient client) {
    // Create an open (schema-less) graph
    client.createGraph("myGraph", GraphType.OPEN, "My first graph");
    System.out.println("Graph created");

    // Create a closed (schema-enforced) graph
    client.createGraph("strictGraph", GraphType.CLOSED, "Schema-enforced graph");

    // Create with default type (OPEN) and no description
    client.createGraph("simpleGraph");
}

Parameters:

Deleting Graphs

dropGraph()

Delete a graph from the database:

Java
public void dropGraphExample(GqldbClient client) {
    // Drop a graph (throws exception if not found)
    client.dropGraph("myGraph");
    System.out.println("Graph dropped");

    // Drop if exists (no error if graph doesn't exist)
    client.dropGraph("maybeGraph", true);
    System.out.println("Graph dropped if it existed");
}

Parameters:

Using a Graph

useGraph()

Set the current graph for the session:

Java
public void useGraphExample(GqldbClient client) {
    // Set the active graph
    client.useGraph("myGraph");
    System.out.println("Now using myGraph");

    // Subsequent queries will target this graph by default
    Response response = client.gql("MATCH (n) RETURN count(n)");
    System.out.println("Node count: " + response.singleLong());
}

Listing Graphs

listGraphs()

Retrieve all graphs in the database:

Java
import com.gqldb.GraphInfo;
import java.util.List;

public void listGraphsExample(GqldbClient client) {
    List<GraphInfo> graphs = client.listGraphs();

    System.out.println("Found " + graphs.size() + " graphs:");
    for (GraphInfo graph : graphs) {
        System.out.println("- " + graph.getName() + " (" + graph.getGraphType() + "): " +
            graph.getDescription());
        System.out.println("  Nodes: " + graph.getNodeCount() + ", Edges: " + graph.getEdgeCount());
    }
}

GraphInfo Class

Java
public class GraphInfo {
    String getName();
    GraphType getGraphType();
    String getDescription();
    long getNodeCount();
    long getEdgeCount();
}

Getting Graph Information

getGraphInfo()

Get detailed information about a specific graph:

Java
public void getGraphInfoExample(GqldbClient client) {
    GraphInfo info = client.getGraphInfo("myGraph");

    System.out.println("Graph Name: " + info.getName());
    System.out.println("Type: " + info.getGraphType());
    System.out.println("Description: " + info.getDescription());
    System.out.println("Node Count: " + info.getNodeCount());
    System.out.println("Edge Count: " + info.getEdgeCount());
}

Exception Handling

Java
import com.gqldb.*;

public void safeGraphOperations(GqldbClient client) {
    try {
        // Try to create a graph
        client.createGraph("newGraph");
    } catch (GraphExistsException e) {
        System.out.println("Graph already exists");
    } catch (GqldbException e) {
        System.err.println("Failed to create graph: " + e.getMessage());
    }

    try {
        // Try to get graph info
        GraphInfo info = client.getGraphInfo("unknownGraph");
    } catch (GraphNotFoundException e) {
        System.out.println("Graph not found");
    }

    try {
        // Try to drop a graph
        client.dropGraph("oldGraph");
    } catch (GraphNotFoundException e) {
        System.out.println("Graph does not exist");
    } catch (GqldbException e) {
        System.err.println("Failed to drop graph: " + e.getMessage());
    }
}

Complete Example

Java
import com.gqldb.*;
import com.gqldb.types.GraphType;
import java.util.List;

public class GraphManagementExample {
    public static void main(String[] args) {
        GqldbConfig config = GqldbConfig.builder()
            .hosts("192.168.1.100:9000")
            .build();

        try (GqldbClient client = new GqldbClient(config)) {
            client.login("admin", "password");

            // List existing graphs
            System.out.println("Existing graphs:");
            List<GraphInfo> existingGraphs = client.listGraphs();
            for (GraphInfo g : existingGraphs) {
                System.out.println("  - " + g.getName());
            }

            // Create a new graph
            String graphName = "demoGraph";
            try {
                client.createGraph(graphName, GraphType.OPEN, "Demo graph for testing");
                System.out.println("Created graph: " + graphName);
            } catch (GraphExistsException e) {
                System.out.println("Graph " + graphName + " already exists");
            }

            // Use the graph
            client.useGraph(graphName);

            // Get graph info
            GraphInfo info = client.getGraphInfo(graphName);
            System.out.println("Graph info: " + info.getName() +
                " (nodes: " + info.getNodeCount() + ", edges: " + info.getEdgeCount() + ")");

            // Insert some data
            client.gql("INSERT (n:User {_id: \"u1\", name: \"Alice\"})");
            client.gql("INSERT (n:User {_id: \"u2\", name: \"Bob\"})");

            // Check updated counts
            GraphInfo updatedInfo = client.getGraphInfo(graphName);
            System.out.println("Graph now has " + updatedInfo.getNodeCount() + " nodes");

            // Clean up - drop the demo graph
            client.dropGraph(graphName);
            System.out.println("Dropped graph: " + graphName);

        } catch (GqldbException e) {
            System.err.println("Error: " + e.getMessage());
        }
    }
}