Network datasets in PostgreSQL
Network datasets are collections of feature classes that possess a connectivity relationship. Network datasets are created using three types of sources—edge feature sources, such as street centerlines; junction feature sources, such as point feature classes containing railroad crossings; and turn feature sources. They are used to model transportation. To use network datasets, you must have the ArcGIS Network Analyst extension installed.
Network datasets in ArcGIS Desktop
In the Catalog tree, feature datasets that contain network datasets in PostgreSQL look the same until you expand the dataset. Once the dataset is expanded, you see the network dataset, which is represented by the following icon:
The name of the network in a geodatabase in PostgreSQL contains the database name, the name of the network owner, and the name of the network itself.
For example, a network dataset, road_network_nd, owned by hbear in the geodatabase m16, would be listed in the Catalog tree as m16.hbear.road_network_nd.
When you create a network dataset, a system junctions feature class is also created. This feature class has the name of the network dataset followed by _Junctions.
Network datasets in a PostgreSQL database
Network datasets are tracked in the gdb_items table. The gdb_itemtypes table stores a value indicating that the object is a network dataset. The gdb_itemrelationships table stores information on how the network and the feature dataset it is in are related.
There are also tables that are created in the schema of the user who owns the network dataset. They are as follows:
- n_<id>_desc: The n_<id>_desc table describes the elements of a network. This is a normalized table whose row count is equal to the number of junctions, edges, and turns in a geometric network.
- n_<id>_props: The n_<id>_props table contains a summary description of a network's properties, such as element counts and maximum EID values.
- n_<id>_topology: This table stores all topology BLOB pages.
- n_<id>_edgeweight: This table stores all BLOB pages for edge weight values.
- n_<id>_junctionweight: This table stores all BLOB pages for junction weight values.
- n_<id>_turnweight: This table stores all BLOB pages for turn weight values.
- nd_<itemid>_dirtyareas: The nd_<itemid>_dirtyareas table stores information about spatial features in the network that have been edited.
- nd_<itemid>_dirtyobjects: The nd_<itemid>_dirtyobjects table stores information about edited relational objects in the network dataset.
The ID in the names of the first six tables is the logicial network ID. The itemID in the last two tables is the objectid from the gdb_items table.
The structures for the tables are as follows:
The n_<id>_desc table contains items for each junction, edge, and turn element in the network dataset.
|
Field name |
Field type |
Description |
Null? |
|---|---|---|---|
|
oid |
integer |
The unique identifier of an element in a network |
NOT NULL |
|
userclassid |
integer |
The identifier of the feature class to which the element belongs |
NOT NULL |
|
userid |
integer |
The ObjectID of the feature |
NOT NULL |
|
usersubid |
integer |
The identifier of an element in a feature; only applicable to complex edge features |
NOT NULL |
|
elementtype |
smallint |
A code indicating the type of network element |
NOT NULL |
|
eid |
integer |
The unique element identifier of the network element; only unique for the type of network element |
NOT NULL |
The n_<id>_props table contains a summary description of a network's properties, such as element counts and maximum EID values.
|
Field name |
Field type |
Description |
Null? |
|---|---|---|---|
|
propertyid |
integer |
The unique identifier of the network property |
NOT NULL |
|
propertyname |
varchar(32) |
The name of the property |
NOT NULL |
|
propertyvalue |
integer |
The value of the property |
NOT NULL |
The nd_<itemid>_dirtyareas table tracks what spatial features in the network dataset have been edited.
Field name | Field type | Description | Null? |
|---|---|---|---|
objectid | integer | Unique identifier for the record | NOT NULL |
isretired | integer | Indicates whether this feature is still used to track the dirty area of a network dataset | NOT NULL |
dirtyarea | st_geometry geometry | The polygon geometry of the dirty area |
The nd_<itemid>_dirtyobjects table tracks edited relational objects in the network dataset such as turns and historical traffic records.
Field name | Field type | Description | Null? |
|---|---|---|---|
objectid | integer | Unique identifier for the record | NOT NULL |
classid | integer | The objectID of the dirty object item in the gdb_items table | NOT NULL |
oid | integer | The object ID of the dirty object | NOT NULL |
updatetype | smallint | The type of edit performed—insert (0), update (1), or delete (2)—that resulted in the dirty object | NOT NULL |
All of the remaining network tables contain the same field names and types. Their structure is as follows:
|
Field name |
Field type |
Description |
Null? |
|---|---|---|---|
|
oid |
integer |
The unique identifier of the bytea page in the table |
NOT NULL |
|
pagenumber |
integer |
The number of the bytea page in the table |
NOT NULL |
|
pageblob |
bytea |
The description for the element the table is describing, such as edge and edge status |
|
|
tableid |
integer |
For the n_<ID>_edgeweight, n_<ID>_turnweight, and n_<ID>_junctionweight BLOB tables, the tableID is the weightID. For the n_<ID>_topology BLOB table, the tableID is the position of the original table within the array of topology tables defined in the GeoDatabase\GeoDatabase\Network\Network\TableDefs.h file. |
NOT NULL |
The following is a diagram of a network dataset in PostgreSQL:
Dashed lines indicate implicit relationships between columns.
There are additional, optional tables you may use as part of your network dataset to model travel times based on historical traffic speeds or denote changes in time zone that could affect network analysis. These are tables that you create prior to creating your network dataset and are stored in your schema (just like the feature class on which a network is built is in the creator's schema). You specify the names of the tables. See the Network Analyst section of the documentation for details on using these historical traffic and time zone tables.
Network datasets in an XML workspace document
Network datasets are tagged as logical networks. The following is an excerpt from an XML document created by exporting from the RoadNetwork dataset.
<LogicalNetworkName>m16.hbear.RoadNetwork_ND</LogicalNetworkName>
<NetworkType>1</NetworkType>
<Buildable>true</Buildable>
<SupportsTurns>true</SupportsTurns>
<Properties xsi:nil="true" />
<UserData xsi:nil="true" />
<EdgeFeatureSources xsi:type="esri:ArrayOfEdgeFeatureSource">
<EdgeFeatureSource xsi:type="esri:EdgeFeatureSource">
<ID>1</ID>
<ClassID>1</ClassID>
<Name>m16.hbear.Streets</Name>
<ElementType>esriNETEdge</ElementType>
<Properties xsi:nil="true" />
<FromElevationFieldName />
<ToElevationFieldName />
<Connectivity xsi:type="esri:PropertySet">
<PropertyArray xsi:type="esri:ArrayOfPropertySetProperty">
<PropertySetProperty xsi:type="esri:PropertySetProperty">
<Key>Version</Key>
<Value xsi:type="xs:short">1</Value>
</PropertySetProperty>
<PropertySetProperty xsi:type="esri:PropertySetProperty">
<Key>UsesSubtypes</Key>
<Value xsi:type="xs:short">0</Value>
</PropertySetProperty>
<PropertySetProperty xsi:type="esri:PropertySetProperty">
<Key>ClassConnectivity</Key>
<Value xsi:type="xs:short">1</Value>
</PropertySetProperty>
<PropertySetProperty xsi:type="esri:PropertySetProperty">
<Key>SubtypeConnCount</Key>
<Value xsi:type="xs:int">0</Value>
</PropertySetProperty>
<PropertySetProperty xsi:type="esri:PropertySetProperty">
<Key>DefaultGroup</Key>
<Value xsi:type="xs:int">1</Value>
</PropertySetProperty>
<PropertySetProperty xsi:type="esri:PropertySetProperty">
<Key>GroupCount</Key>
<Value xsi:type="xs:int">0</Value>
</PropertySetProperty>
</PropertyArray>
</Connectivity>
</EdgeFeatureSource>
</EdgeFeatureSources>
<JunctionFeatureSources xsi:type="esri:ArrayOfJunctionFeatureSource" />
<SystemJunctionSources xsi:type="esri:ArrayOfSystemJunctionSource">
<SystemJunctionSource xsi:type="esri:SystemJunctionSource">
<ID>3</ID>
<ClassID>4</ClassID>
<Name>m16.hbear.RoadNetwork_ND_Junctions</Name>
<ElementType>esriNETJunction</ElementType>
<Properties xsi:nil="true" />
<ElevationFieldName />
</SystemJunctionSource>
</SystemJunctionSources>
<TurnFeatureSources xsi:type="esri:ArrayOfTurnFeatureSource">
<TurnFeatureSource xsi:type="esri:TurnFeatureSource">
<ID>2</ID>
<ClassID>2</ClassID>
<Name>m16.hbear.Turns</Name>
<ElementType>esriNETTurn</ElementType>
<Properties xsi:nil="true" />
</TurnFeatureSource>
</TurnFeatureSources>
<EvaluatedNetworkAttributes xsi:type="esri:ArrayOfEvaluatedNetworkAttribute">
<EvaluatedNetworkAttribute xsi:type="esri:EvaluatedNetworkAttribute">
<ID>1</ID>
<Name>Oneway</Name>
<Units>Unknown</Units>
<DataType>esriNADTBoolean</DataType>
<UsageType>esriNAUTRestriction</UsageType>
<UserData xsi:nil="true" />
<UseByDefault>true</UseByDefault>
<AttributeParameters xsi:type="esri:ArrayOfNetworkAttributeParameter" />
</EvaluatedNetworkAttribute>
</EvaluatedNetworkAttributes>