BFS - Category

Traversal using breadth first search.

  • It’s implementation is only on undirected graph.

  • Process is done only on edges with positive costs.

  • When the graph is connected

    • The resulting edges make up a tree

  • When the graph is not connected,

    • Finds a minimum spanning tree for each connected component.

    • The resulting edges make up a forest.

Parameters

Parameter

Type

Description

Edges SQL

TEXT

Edges SQL as described below.

root vid

BIGINT

Identifier of the root vertex of the tree.

  • When value is \(0\) then gets the spanning forest starting in aleatory nodes for each tree in the forest.

root vids

ARRAY [ ANY-INTEGER ]

Array of identifiers of the root vertices.

  • \(0\) values are ignored

  • For optimization purposes, any duplicated value is ignored.

Where:

ANY-INTEGER :

SMALLINT, INTEGER, BIGINT

ANY-NUMERIC :

SMALLINT, INTEGER, BIGINT, REAL, FLOAT, NUMERIC

BFS optional parameters

Parameter

Type

Default

Description

max_depth

BIGINT

\(9223372036854775807\)

Upper limit of the depth of the tree.

  • When negative throws an error.

Inner Queries

Edges SQL

Column

Type

Default

Description

id

ANY-INTEGER

Identifier of the edge.

source

ANY-INTEGER

Identifier of the first end point vertex of the edge.

target

ANY-INTEGER

Identifier of the second end point vertex of the edge.

cost

ANY-NUMERICAL

Weight of the edge ( source , target )

reverse_cost

ANY-NUMERICAL

-1

Weight of the edge ( target , source )

  • When negative: edge ( target , source ) does not exist, therefore it’s not part of the graph.

Where:

ANY-INTEGER :

SMALLINT , INTEGER , BIGINT

ANY-NUMERICAL :

SMALLINT , INTEGER , BIGINT , REAL , FLOAT

Result Columns

Returns SET OF (seq, depth, start_vid, node, edge, cost, agg_cost)

Parameter

Type

Description

seq

BIGINT

Sequential value starting from \(1\) .

depth

BIGINT

Depth of the node .

  • \(0\) when node = start_vid .

start_vid

BIGINT

Identifier of the root vertex.

node

BIGINT

Identifier of node reached using edge .

edge

BIGINT

Identifier of the edge used to arrive to node .

  • \(-1\) when node = start_vid .

cost

FLOAT

Cost to traverse edge .

agg_cost

FLOAT

Aggregate cost from start_vid to node .

Where:

ANY-INTEGER :

SMALLINT, INTEGER, BIGINT

ANY-NUMERIC :

SMALLINT, INTEGER, BIGINT, REAL, FLOAT, NUMERIC

See Also

Indices and tables