# Via - Category¶

proposed

Warning

Proposed functions for next mayor release.

• They are not officially in the current release.

• They will likely officially be part of the next mayor release:

• The functions make use of ANY-INTEGER and ANY-NUMERICAL

• Name might not change. (But still can)

• Signature might not change. (But still can)

• Functionality might not change. (But still can)

• pgTap tests have being done. But might need more.

• Documentation might need refinement.

## General Information¶

This category intends to solve the general problem:

Given a graph and a list of vertices, find the shortest path between $$vertex_i$$ and $$vertex_{i+1}$$ for all vertices

In other words, find a continuos route that visits all the vertices in the order given.

path:

represents a section of a route.

route:

is a sequence of paths

## Parameters¶

Used on:

Parameter

Type

Default

Description

Edges SQL

TEXT

SQL query as described.

via vertices

ARRAY[ ANY-INTEGER ]

Array of ordered vertices identifiers that are going to be visited.

Where:

ANY-INTEGER:

SMALLINT, INTEGER, BIGINT

ANY-NUMERICAL:

SMALLINT, INTEGER, BIGINT, REAL, FLOAT

Besides the compulsory parameters each function has, there are optional parameters that exist due to the kind of function.

### Via optional parameters¶

Used on all Via functions

Parameter

Type

Default

Description

strict

BOOLEAN

false

• When true if a path is missing stops and returns EMPTY SET

• When false ignores missing paths returning all paths found

U_turn_on_edge

BOOLEAN

true

• When true departing from a visited vertex will not try to avoid

## Inner Queries¶

Depending on the function one or more inner queries are needed.

### 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

### Restrictions SQL¶

Column

Type

Description

path

ARRAY[ ANY-INTEGER ]

Sequence of edge identifiers that form a path that is not allowed to be taken. - Empty arrays or NULL arrays are ignored. - Arrays that have a NULL element will raise an exception.

Cost

ANY-NUMERICAL

Cost of taking the forbidden path.

Where:

ANY-INTEGER:

SMALLINT, INTEGER, BIGINT

ANY-NUMERICAL:

SMALLINT, INTEGER, BIGINT, REAL, FLOAT

## Result Columns¶

Column

Type

Description

seq

INTEGER

Sequential value starting from 1.

path_id

INTEGER

Identifier of a path. Has value 1 for the first path.

path_seq

INTEGER

Relative position in the path. Has value 1 for the beginning of a path.

start_vid

BIGINT

Identifier of the starting vertex of the path.

end_vid

BIGINT

Identifier of the ending vertex of the path.

node

BIGINT

Identifier of the node in the path from start_vid to end_vid.

edge

BIGINT

Identifier of the edge used to go from node to the next node in the path sequence.

• -1 for the last node of the path.

• -2 for the last node of the route.

cost

FLOAT

Cost to traverse from node using edge to the next node in the path sequence.

agg_cost

FLOAT

Aggregate cost from start_vid to node.

route_agg_cost

FLOAT

Total cost from start_vid of seq = 1 to end_vid of the current seq.

Note

When start_vid, end_vid and node columns have negative values, the identifier is for a Point.