# pgRouting Manual (3.0-rc1)

## pgr_maxFlowMinCost_Cost - Experimental

`pgr_maxFlowMinCost_Cost` — Calculates the minmum cost maximum flow in a directed graph from the source(s) to the targets(s).

Boost Graph Inside

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:

- The graph is directed.
- The cost value of all input edges must be nonnegative.
- When the maximum flow is 0 then there is no flow and 0 is returned.
  - There is no flow when a source is the same as a target.
- Any duplicated value in the source(s) or target(s) are ignored.
- Uses the pgr_maxFlowMinCost algorithm.

- Running time: \(O(U * (E + V * logV))\), where \(U\) is the value of the max flow. \(U\) is upper bound on number of iteration. In many real world cases number of iterations is much smaller than \(U\).

## Signatures

Summary

    pgr_maxFlowMinCost_Cost(Edges SQL, source, target)
    pgr_maxFlowMinCost_Cost(Edges SQL, sources, target)
    pgr_maxFlowMinCost_Cost(Edges SQL, source, targets)
    pgr_maxFlowMinCost_Cost(Edges SQL, sources, targets)
    RETURNS FLOAT

### One to One

    pgr_maxFlowMinCost_Cost(Edges SQL, source, target)
    RETURNS FLOAT

Example: | From vertex \(2\) to vertex \(3\)

    SELECT * FROM pgr_MaxFlowMinCost_Cost(
        'SELECT id,
         source, target,
         capacity, reverse_capacity,
         cost, reverse_cost FROM edge_table',
        2, 3
    );
     pgr_maxflowmincost_cost
    -------------------------
                         400
    (1 row)

### One to Many

    pgr_maxFlowMinCost_Cost(Edges SQL, source, targets)
    RETURNS FLOAT

Example: | From vertex \(13\) to vertices \(\{7, 1, 4\}\)

    SELECT * FROM pgr_MaxFlowMinCost_Cost(
        'SELECT id,
         source, target,
         capacity, reverse_capacity,
         cost, reverse_cost FROM edge_table',
        13, ARRAY[7, 1, 4]
    );
     pgr_maxflowmincost_cost
    -------------------------
                         450
    (1 row)

### Many to One

    pgr_maxFlowMinCost_Cost(Edges SQL, sources, target)
    RETURNS FLOAT

Example: | From vertices \(\{1, 7, 14\}\) to vertex \(12\)

    SELECT * FROM pgr_MaxFlowMinCost_Cost(
        'SELECT id,
         source, target,
         capacity, reverse_capacity,
         cost, reverse_cost FROM edge_table',
        ARRAY[1, 7, 14], 12
    );
     pgr_maxflowmincost_cost
    -------------------------
                         650
    (1 row)

### Many to Many

    pgr_maxFlowMinCost_Cost(Edges SQL, sources, targets)
    RETURNS FLOAT

Example: | From vertices \(\{7, 13\}\) to vertices \(\{3, 9\}\)

    SELECT * FROM pgr_MaxFlowMinCost_Cost(
        'SELECT id,
         source, target,
         capacity, reverse_capacity,
         cost, reverse_cost FROM edge_table',
        ARRAY[7, 13], ARRAY[3, 9]
    );
     pgr_maxflowmincost_cost
    -------------------------
                         600
    (1 row)

## Parameters

Column | Type | Default | Description
--- | --- | --- | ---
Edges SQL | `TEXT` |  | The edges SQL query as described in Inner Query.
source | `BIGINT` |  | Identifier of the starting vertex of the flow.
sources | `ARRAY[BIGINT]` |  | Array of identifiers of the starting vertices of the flow.
target | `BIGINT` |  | Identifier of the ending vertex of the flow.
targets | `ARRAY[BIGINT]` |  | Array of identifiers of the ending vertices of the flow.

## Inner query

Edges SQL: | an SQL query of a directed graph of capacities, which should return a set of rows 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.

capacity

`ANY-INTEGER`

Capacity of the edge (source, target)

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

reverse_capacity

`ANY-INTEGER`

-1

Capacity of the edge (target, source),

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

cost | `ANY-NUMERICAL` |  | Weight of the edge (source, target) if it exists.
reverse_cost | `ANY-NUMERICAL` | 0 | Weight of the edge (target, source) if it exists.

Where:

ANY-INTEGER: | SMALLINT, INTEGER, BIGINT
ANY-NUMERICAL: | smallint, int, bigint, real, float

## Result Columns

Type | Description
--- | ---
`FLOAT` | Minimum Cost Maximum Flow possible from the source(s) to the target(s)

## See Also

- Flow - Family of functions
- https://www.boost.org/libs/graph/doc/successive_shortest_path_nonnegative_weights.html

Indices and tables

- Index
- Search Page