Supported versions: latest (3.8) 3.7 3.6 3.5 3.4 3.3 3.2 3.1 3.0 main dev

`pgr_transitiveClosure` - Experimental¶

pgr_transitiveClosure — Transitive closure graph of a directed graph.

Experimental

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 community.
- Might depend on a proposed function of pgRouting
- Might depend on a deprecated function of pgRouting

Availability

Version 4.0.0

Standardized output to (node,targets)

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 compressed
Running time: $O (| V | | E |)$

Boost Graph Inside

Signatures¶

Summary

The pgr_transitiveClosure function has the following signature:

pgr_transitiveClosure(Edges SQL)

Returns set of (node,targets)

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 node;
 node |      targets
------+--------------------
    6 | {}
    8 | {12,17,16}
   10 | {12,17,16,11,6}
   11 | {12,17,16}
   12 | {17,16}
   15 | {12,17,16,10,11,6}
   16 | {17,16}
   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 (node,targets)

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.

pgr_transitiveClosure - Experimental¶