Graph Registry

Onager provides an in-memory graph registry that stores named graphs for efficient repeated queries.

When to Use the Registry

• When querying the same graph multiple times
• When querying node or graph statistics
• When you want to run different queries or algorithms on the same graph

Creating Graphs

-- Create a directed graph
select onager_create_graph('social', true);

-- Create an undirected graph
select onager_create_graph('network', false);

Adding Data

-- Add nodes
select onager_add_node('social', 1);
select onager_add_node('social', 2);
select onager_add_node('social', 3);

-- Add edges (with weights)
select onager_add_edge('social', 1, 2, 1.0);
select onager_add_edge('social', 1, 3, 0.5);
select onager_add_edge('social', 2, 3, 1.0);

Querying Graphs

-- Get graph statistics
select onager_node_count('social'); -- 3
select onager_edge_count('social');
-- 3

-- Query node degrees
select onager_node_in_degree('social', 3); -- 2 (from nodes 1 and 2)
select onager_node_out_degree('social', 1); -- 2 (to nodes 2 and 3)

Managing Graphs

-- List all graphs
select onager_list_graphs();
-- '["social", "network"]'

-- Delete a graph
select onager_drop_graph('social');

Graph Registry vs Table Functions

Feature	Graph Registry	Table Functions
Data storage	In-memory	Per-query
Query type	Scalar (single values)	Table (result sets)
Best for	Point queries, repeated access	One-time analysis
Example	onager_node_in_degree('g', 1)	onager_ctr_pagerank(edges)

Example: Social Network Analysis

-- Setup
select onager_create_graph('friends', true);

-- Create sample user data
create table users as select * from (values (1::bigint), (2), (3), (4), (5)) t(user_id);
create table follows as select * from (values
  (1::bigint, 2::bigint), (1, 3), (2, 3), (2, 4), (3, 4), (3, 5)
) t(follower_id, followed_id);

-- Bulk load from table
select onager_add_node('friends', user_id)
from users;
select onager_add_edge('friends', follower_id, followed_id, 1.0)
from follows;

-- Query influential users (high out-degree)
select user_id, onager_node_out_degree('friends', user_id) as followers
from users
order by followers desc limit 10;

-- Cleanup
select onager_drop_graph('friends');