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Input Formats

Table Functions

Table functions expect edges as a subquery with two bigint columns:

create table my_edges as select * from (values (1::bigint, 2::bigint), (2, 3)) t(src, dst);

select *
from onager_ctr_pagerank((select src, dst from my_edges));

Named Graphs

Scalar functions operate on named graphs stored in the registry:

select onager_create_graph('social', true);
select onager_add_node('social', 1);
select onager_node_in_degree('social', 1);

Edge list format

Onager uses edge lists, not adjacency matrices. Each row represents one edge with a source and destination node.

Node IDs

Node IDs must be bigint integers. They do not need to be continuous or start from zero. Any integer value works, like 1, 2, 3 or 100, 200, 500.

Directed vs undirected

Every function treats the edge list as undirected by default. Direction-sensitive functions (centrality, traversal, shortest paths, the diameter, radius, average path length, assortativity, and density metrics, and the parallel PageRank, BFS, and shortest path variants) accept directed := true to treat each edge row as one-way. See the SQL Function Reference for the functions that take the parameter. Note that edges are not deduplicated, so passing both (1, 2) and (2, 1) to an undirected function creates two parallel edges between the nodes.

Weighted functions

Some functions accept edge weights as a third column. These include:

  • onager_pth_bellman_ford: Shortest paths with negative weights
  • onager_pth_floyd_warshall: All-pairs shortest paths
  • onager_mst_kruskal: Minimum spanning tree (Kruskal's)
  • onager_mst_prim: Minimum spanning tree (Prim's)
  • onager_apx_tsp: Traveling salesman approximation
  • onager_pth_dijkstra: Shortest paths with nonnegative weights (the weights column is optional)

onager_ctr_pagerank and onager_par_pagerank also use a third double column as edge weights when it is present, and fall back to weight 1.0 for every edge when it is absent. Weight values must not be NULL or NaN, and PageRank additionally rejects negative weights.

Pass weights like this: 

create table edges as select * from (values
  (1::bigint, 2::bigint, 1.0::double), (2, 3, 2.0), (3, 4, 1.5)
) t(src, dst, weight);

select * from onager_mst_kruskal((select src, dst, weight from edges));