Features read from PostGIS consist of a series of attribute values and geometry. The feature type of each feature is as defined on its DEF line. The geometry object model in PostGIS follows the OGIS Simple Features Specification 1.1. For more information see http://www.opengis.org.
Features written to the database have the destination table as their feature type, and attributes as defined on the DEF line.
In addition to the generic FME feature attributes that FME Workbench adds to all features (see About Feature Attributes), this format adds the format-specific attributes described in this topic.
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Attribute Name |
Contents |
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postgis_type |
The type of geometric entity stored within the feature. The valid values for the object model are listed below: postgis_point postgis_multipoint postgis_linestring postgis_multilinestring postgis_circularstring postgis_compoundcurve postgis_multicurve postgis_polygon postgis_multipolygon postgis_curvepolygon postgis_multisurface postgis_triangle postgis_polyhedralsurface postgis_tin postgis_geometrycollection postgis_none |
| postgres_oid | Tables in a PostgreSQL database may be created with an OID column, although this is typically used only by system tables. This attribute is present and set to the value of the OID column if it is present in the table being read. |
Features read from, or written to, PostGIS also have an attribute for each column in the database table. The feature attribute name will be the same as the source or destination column name. The attribute and column names are case-sensitive.
No Coordinates
postgis_type: postgis_none
Features with no coordinates are tagged with this value when reading from PostGIS. Note that when reading or writing attribute-only data tables, the PostgreSQL reader/writer should be used instead. Note also that this is not a valid OGC type.
Point
postgis_type: postgis_point
Features tagged with this value consist of a single point.
MultiPoint
postgis_type: postgis_multipoint
Features tagged with this value consist of a collection of points.
LineString
postgis_type: postgis_linestring
Features tagged with this value consist of a single line.
MultiLineString
postgis_type: postgis_multilinestring
Features tagged with this value consist of a collection of lines.
CircularString
postgis_type: postgis_circularstring
Features tagged with this value consist of a path of circular arcs.
CompoundCurve
postgis_type: postgis_compoundcurve
Features tagged with this value consist of a path of lines and/or circular arcs.
MultiCurve
postgis_type: postgis_multicurve
Features tagged with this value consist of a collection of lines and paths of circular arcs.
Note that paths containing both lines and circular arcs may not be stored in a MultiCurve.
Polygon
postgis_type: postgis_polygon
Features tagged with this value consist of a linear polygon or donut.
MultiPolygon
postgis_type: postgis_multipolygon
Features tagged with this value consist of a collection of linear polygons and/or donuts.
CurvePolygon
postgis_type: postgis_curvepolygon
Features tagged with this value consist of a linear or curved polygon or donut.
MultiSurface
postgis_type: postgis_multisurface
Features tagged with this value consist of a collection of linear and/or curved polygons and/or donuts.
Triangle
postgis_type: postgis_triangle
Features tagged with this value consist of a linear triangular polygon, with X, Y, and Z components on each vertex.
PolyhedralSurface
postgis_type: postgis_polyhedralsurface
Features tagged with this value consist of a collection of linear polygons (not donuts) forming a single contiguous orientable non-self-intersecting surface. The vertices of these polygons have X, Y, and Z components.
TIN
postgis_type: postgis_tin
Features tagged with this value are PolyhedralSurfaces where every polygon in the feature is a triangle.
GeometryCollection
postgis_type: postgis_geometrycollection
Features tagged with this value consist of a possibly heterogeneous aggregate.
When writing to PostGIS, the postgis_type can be manually set to postgis_geometrycollection and features will be combined into collections based on the postgis_collection_id attribute.
Geometry
postgis_type: postgis_geometry
Although not a valid geometry type on an individual feature, this type may be set for the destination geometry column type to indicate that any geometry is allowable in that column. If the writer directive GENERIC_GEOMETRY is specified at generation time, all destination feature types will have geometry columns of this type. Alternatively, although it will not happen by default, this type can be specified on any one or more destination feature types manually to create generic geometry columns on those specific tables.
Note that although the geometry column is explicitly determined by the user when writing, the reader will attempt to determine the geometry column name and type using the PostGIS metadata tables.
In cases where the PostGIS reader is applied to databases lacking the proper metadata tables or entries, then the first column whose type would allow for geometry storage is taken as the geometry column. This decision may cause the translation to fail if the column does not indeed contain geometry. To work around this case, please use the PostgreSQL reader instead, which ignores geometry columns. Alternatively, if there are multiple geometry columns or a mixture of blob columns and geometry columns and the geometry is still desired, try formatting a custom SQL query that selects the geometry column the first column.
Note also that geometry columns can be stored in either geometry or blob columns but these may contain other data as well. Geometry columns that do not correspond to the geometry of the feature will be read as hex-encoded strings and blobs will be read as raw bytes.