Spatial functions
Use specific spatial data type functions to perform operations on spatial data.
- Determine spatial relationships: You can determine whether a specific
relationship exists between a pair of geometries.
The distance that separates a hazardous waste disposal site and a school is an example of a spatial relationship.
- Produce a new geometry: You can compare two existing geometries
and return a new geometry that is based on how the two geometries
are related.
For example, the ST_Difference() function returns that portion of the first geometry that is not intersected or overlapped by the second.
- Transform geometries: You can generate a new geometry from an existing geometry and a formula.
Functions can compare two geometries if the SRIDs of the arguments are the same. To compare two geometries that have different SRIDs, use the ST_Transform() function to transform one of the geometries.
The Dimensionally Extended 9 Intersection Model (DE-9IM) is a mathematical approach that defines the pair-wise spatial relationship between geometries of different types and dimensions.
Most spatial data functions are compliant
with OpenGIS and ISO/SQLMM standards and have the prefix ST_.
Some spatial data functions extend the OpenGIS and ISO/SQLMM standards
and have the prefix SE_.
| Compliant function | Extension function |
|---|---|
| ST_Is3D() | SE_Is3D() |
| ST_IsMeasured() | SE_IsMeasured() |
| ST_LocateAlong() | SE_LocateAlong() |
| ST_LocateBetween() | SE_LocateBetween() |
| ST_M() | SE_M() |
| ST_Z() | SE_Z() |
| ST_MaxM() | SE_MMax() |
| ST_MinM() | SE_MMin() |
| ST_MaxX() | SE_XMax() |
| ST_MinX() | SE_XMin() |
| ST_MaxY() | SE_YMax() |
| ST_MinY() | SE_YMin() |
| ST_MaxZ() | SE_ZMax() |
| ST_MaxZ() | SE_ZMin() |