pgr_transitiveClosure - Experimental

pgr_transitiveClosure - Transitive closure graph of a directed graph.

images/boost-inside.jpeg

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

Description

Transforms the input directed graph into the transitive closure of the graph.

The main characteristics are:

  • Process is valid for directed graphs.

    • The transitive closure of an undirected graph produces a cluster graph

    • Reachability between vertices on an undirected graph happens when they belong to the same connected component. (see pgr_connectedComponents )

  • The returned values are not ordered

  • The returned graph is compresed

  • Running time: \(O(VE)\)

Signatures

Summary

The pgr_transitiveClosure function has the following signature:

pgr_transitiveClosure( Edges SQL )
RETURNS SET OF (seq, vid, target_array)
Example :

Rechability of a subgraph 

SELECT * FROM pgr_transitiveclosure(
  'SELECT id, source, target, cost, reverse_cost
  FROM edges WHERE id IN (2, 3, 5, 11, 12, 13, 15)')
ORDER BY vid;
 seq  vid     target_array
-----+-----+--------------------
   1    6  {}
   6    8  {12,17,16}
   2   10  {12,17,16,11,6}
   4   11  {12,17,16}
   5   12  {17,16}
   3   15  {12,17,16,10,11,6}
   8   16  {17,16}
   7   17  {17,16}
(8 rows)

Parameters

Parameter

Type

Description

Edges SQL

TEXT

Edges SQL as described below.

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, vid, target_array)

Column

Type

Description

seq

INTEGER

Sequential value starting from \(1\)

vid

BIGINT

Identifier of the source of the edges

target_array

BIGINT

Identifiers of the targets of the edges

  • Identifiers of the vertices that are reachable from vertex v.

See Also

Indices and tables