# pgRouting Manual (3.0-rc1)

## 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 function

Support

- Supported versions current(3.0)

## 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.

- [TBD] 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 edge_table where id < 17'
    );
     pgr_chinesepostmancost
    ------------------------
                         34
    (1 row)

## Parameters

Column | Type | Default | Description
--- | --- | --- | ---
edges_sql | `TEXT` |  | The edges SQL query as described in Inner query.

## Inner query

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)

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

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

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

## See Also

- Chinese Postman Problem - Family of functions (Experimental)

Indices and tables

- Index
- Search Page