# BFS - Category¶

• 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