pgRouting Manual (2.0.0)

pgr_createVerticesTable

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pgr_createVerticesTable

Name

pgr_createVerticesTable — Reconstructs the vertices table based on the source and target information.

Synopsis

The function returns:

  • OK after the vertices table has been reconstructed.
  • FAIL when the vertices table was not reconstructed due to an error.
varchar pgr_createVerticesTable(text edge_table,  text the_geom:='the_geom'
                   text source:='source',text target:='target',text rows_where:='true')

Description

Parameters

The reconstruction of the vertices table function accepts the following parameters:

edge_table:text Network table name. (may contain the schema name as well)
the_geom:text Geometry column name of the network table. Default value is the_geom.
source:text Source column name of the network table. Default value is source.
target:text Target column name of the network table. Default value is target.
rows_where:text Condition to SELECT a subset or rows. Default value is true to indicate all rows.

Warning

The edge_table will be affected

  • An index will be created, if it doesn’t exists, to speed up the process to the following columns:

    • the_geom
    • source
    • target

The function returns:

  • OK after the vertices table has been reconstructed.
    • Creates a vertices table: <edge_table>_vertices_pgr.
    • Fills id and the_geom columns of the vertices table based on the source and target columns of the edge table.
  • FAIL when the vertices table was not reconstructed due to an error.
    • A required column of the Network table is not found or is not of the appropriate type.
    • The condition is not well formed.
    • The names of source, target are the same.
    • The SRID of the geometry could not be determined.

The Vertices Table

The vertices table is a requierment of the pgr_analyzeGraph and the pgr_analyzeOneway functions.

The structure of the vertices table is:

id:bigint Identifier of the vertex.
cnt:integer Number of vertices in the edge_table that reference this vertex. See pgr_analyzeGraph.
chk:integer Indicator that the vertex might have a problem. See pgr_analyzeGraph.
ein:integer Number of vertices in the edge_table that reference this vertex as incoming. See pgr_analyzeOneway.
eout:integer Number of vertices in the edge_table that reference this vertex as outgoing. See pgr_analyzeOneway.
the_geom:geometry Point geometry of the vertex.

History

  • Renamed in version 2.0.0

Usage when the edge table’s columns MATCH the default values:

The simplest way to use pgr_createVerticesTable is:

SELECT  pgr_createVerticesTable('edge_table');

When the arguments are given in the order described in the parameters:

SELECT  pgr_createVerticesTable('edge_table','the_geom','source','target');

We get the same result as the simplest way to use the function.

Warning

An error would occur when the arguments are not given in the appropriate order: In this example, the column source column source of the table mytable is passed to the function as the geometry column, and the geometry column the_geom is passed to the function as the source column.
SELECT  pgr_createVerticesTable('edge_table','source','the_geom','target');

When using the named notation

The order of the parameters do not matter:

SELECT  pgr_createVerticesTable('edge_table',the_geom:='the_geom',source:='source',target:='target');
SELECT  pgr_createVerticesTable('edge_table',source:='source',target:='target',the_geom:='the_geom');

Parameters defined with a default value can be omited, as long as the value matches the default:

SELECT  pgr_createVerticesTable('edge_table',source:='source');

Selecting rows using rows_where parameter

Selecting rows based on the id.

SELECT  pgr_createVerticesTable('edge_table',rows_where:='id < 10');

Selecting the rows where the geometry is near the geometry of row with id =5 .

SELECT  pgr_createVerticesTable('edge_table',rows_where:='the_geom && (select st_buffer(the_geom,0.5) FROM edge_table WHERE id=5)');

Selecting the rows where the geometry is near the geometry of the row with gid =100 of the table othertable.

DROP TABLE IF EXISTS otherTable;
CREATE TABLE otherTable AS  (SELECT 100 AS gid, st_point(2.5,2.5) AS other_geom) ;
SELECT  pgr_createVerticesTable('edge_table',rows_where:='the_geom && (select st_buffer(othergeom,0.5) FROM otherTable WHERE gid=100)');

Usage when the edge table’s columns DO NOT MATCH the default values:

For the following table

DROP TABLE IF EXISTS mytable;
CREATE TABLE mytable AS (SELECT id AS gid, the_geom AS mygeom,source AS src ,target AS tgt FROM edge_table) ;

Using positional notation:

The arguments need to be given in the order described in the parameters:

SELECT  pgr_createVerticesTable('mytable','mygeom','src','tgt');

Warning

An error would occur when the arguments are not given in the appropriate order: In this example, the column src of the table mytable is passed to the function as the geometry column, and the geometry column mygeom is passed to the function as the source column.
SELECT  pgr_createVerticesTable('mytable','src','mygeom','tgt');

When using the named notation

The order of the parameters do not matter:

SELECT  pgr_createVerticesTable('mytable',the_geom:='mygeom',source:='src',target:='tgt');
SELECT  pgr_createVerticesTable('mytable',source:='src',target:='tgt',the_geom:='mygeom');

In this scenario omitting a parameter would create an error because the default values for the column names do not match the column names of the table.

Selecting rows using rows_where parameter

Selecting rows based on the gid.

SELECT  pgr_createVerticesTable('mytable','mygeom','src','tgt',rows_where:='gid < 10');
SELECT  pgr_createVerticesTable('mytable',source:='src',target:='tgt',the_geom:='mygeom',rows_where:='gid < 10');

Selecting the rows where the geometry is near the geometry of row with gid =5 .

SELECT  pgr_createVerticesTable('mytable','mygeom','src','tgt',
                           rows_where:='the_geom && (SELECT st_buffer(mygeom,0.5) FROM mytable WHERE gid=5)');
SELECT  pgr_createVerticesTable('mytable',source:='src',target:='tgt',the_geom:='mygeom',
                           rows_where:='mygeom && (SELECT st_buffer(mygeom,0.5) FROM mytable WHERE id=5)');

Selecting the rows where the geometry is near the geometry of the row with gid =100 of the table othertable.

DROP TABLE IF EXISTS otherTable;
CREATE TABLE otherTable AS  (SELECT 100 AS gid, st_point(2.5,2.5) AS other_geom) ;
SELECT  pgr_createVerticesTable('mytable','mygeom','src','tgt',
                            rows_where:='the_geom && (SELECT st_buffer(othergeom,0.5) FROM otherTable WHERE gid=100)');
SELECT  pgr_createVerticesTable('mytable',source:='src',target:='tgt',the_geom:='mygeom',
                            rows_where:='the_geom && (SELECT st_buffer(othergeom,0.5) FROM otherTable WHERE gid=100)');

Examples

    SELECT pgr_createVerticesTable('edge_table');
    NOTICE:  PROCESSING:
NOTICE:  pgr_createVerticesTable('edge_table','the_geom','source','target','true')
NOTICE:  Performing checks, pelase wait .....
NOTICE:  Populating public.edge_table_vertices_pgr, please wait...
NOTICE:    ----->   VERTICES TABLE CREATED WITH  17 VERTICES
NOTICE:                                         FOR   18  EDGES
NOTICE:    Edges with NULL geometry,source or target: 0
NOTICE:                              Edges processed: 18
NOTICE:  Vertices table for table public.edge_table is: public.edge_table_vertices_pgr
NOTICE:  ----------------------------------------------

     pgr_createVerticesTable
    --------------------
     OK
    (1 row)

The example uses the Sample Data network.

See Also

«  pgr_createTopology   ::   Contents   ::   pgr_analyzeGraph  »