# pgRouting Manual (3.6)

## pgr_chinesePostmanCost - Experimental

# `pgr_chinesePostmanCost` - Experimental

`pgr_chinesePostmanCost` — Calculates the minimum costs of a circuit path which contains every edge in a directed graph and starts and ends on the same vertex.

Warning

Possible server crash

- These functions might create a server crash

Warning

Experimental functions

- They are not officially of the current release.

- They likely will not be officially be part of the next release:

  - The functions might not make use of ANY-INTEGER and ANY-NUMERICAL

  - Name might change.

  - Signature might change.

  - Functionality might change.

  - pgTap tests might be missing.

  - Might need c/c++ coding.

  - May lack documentation.

  - Documentation if any might need to be rewritten.

  - Documentation examples might need to be automatically generated.

  - Might need a lot of feedback from the comunity.

  - Might depend on a proposed function of pgRouting

  - Might depend on a deprecated function of pgRouting

Availability

- Version 3.0.0

  - New experimental signature

## Description

The main characteristics are:

- Process is done only on edges with positive costs.

- Running time: \(O(E * (E + V * logV))\)

- Graph must be connected.

- Return value when the graph if disconnected

## Signatures

pgr_chinesePostmanCost(Edges SQL)
RETURNS `FLOAT`

Example:

    SELECT * FROM pgr_chinesePostmanCost(
      'SELECT id, source, target, cost, reverse_cost
      FROM edges WHERE id < 17');
     pgr_chinesepostmancost
    ------------------------
                         34
    (1 row)

## Parameters

Parameter | Type | Description
--- | --- | ---
Edges SQL | `TEXT` | Edges SQL as described below.

## Inner Queries

### Edges SQL

An Edges SQL that represents a directed graph with the following columns

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

Column | Type | Description
--- | --- | ---
`pgr_chinesepostmancost` | `FLOAT` | Minimum costs of a circuit path.

## See Also

- Chinese Postman Problem - Family of functions (Experimental)

- Sample Data

Indices and tables

- Index

- Search Page