Contents
What does St dump-PostGIS do in geometry?
ST_Dump — Returns a set of geometry_dump rows for the components of a geometry. This is a set-returning function (SRF). It returns a set of geometry_dump rows, formed by a geometry (geom) and an array of integers (path).
When to use St dump in a multi?
When the input geometry is a collection or multi it will return a record for each of the collection components, and the path will express the position of the component inside the collection. ST_Dump is useful for expanding geometries. It is the reverse of a GROUP BY in that it creates new rows.
Which is the reverse of a group St dump?
ST_Dump is useful for expanding geometries. It is the reverse of a GROUP BY in that it creates new rows. For example it can be use to expand MULTIPOLYGONS into POLYGONS.
What happens when the Input geometry is a simple type?
When the input geometry is a simple type (POINT,LINESTRING,POLYGON) a single record will be returned with an empty path array and the input geometry as geom.
How does the St Union array in PostGIS 14 work?
The ST_Union array and set variants use the fast Cascaded Union algorithm described in http://blog.cleverelephant.ca/2009/01/must-faster-unions-in-postgis-14.html A gridSize can be specified to work in fixed-precision space. The inputs are snapped to a grid of the given size, and the result vertices are computed on that same grid.
How to enumerate a point in St _ dumppoints?
If a POLYGON is supplied, a path of {i,j} is returned where i is the ring number (1 is outer; inner rings follow) and j enumerates the POINT s (again 1-based index). Enhanced: 2.1.0 Faster speed. Reimplemented as native-C. Enhanced: 2.0.0 support for Polyhedral surfaces, Triangles and TIN was introduced.
When the input geometry is a collection or multi it will return a record for each of the collection components, and the path will express the position of the component inside the collection. ST_Dump is useful for expanding geometries.
What can St dump be used for in Excel?
ST_Dump is useful for expanding geometries. It is the reverse of a GROUP BY in that it creates new rows. For example it can be use to expand MULTIPOLYGONS into POLYGONS. Enhanced: 2.0.0 support for Polyhedral surfaces, Triangles and TIN was introduced.