Extended Well-Known Text (EWKT) extends the standard Well-Known Text (WKT) format by adding a spatial reference identifier (SRID) and an optional SOLID flag. PolarDB for PostgreSQL uses EWKT for spatial data that carries coordinate reference system metadata.
Segments in an EWKT string are separated by semicolons (;).
Syntax
An EWKT string follows this structure:
SRID=<srid>;<geometry-type>(<coordinates>)To include the SOLID flag:
SRID=<srid>;SOLID=true;<geometry-type>(<coordinates>)Key components
| Component | Description |
|---|---|
SRID | The spatial reference identifier that specifies the coordinate reference system. |
SOLID | An optional boolean flag. Set to true to mark the geometry as a solid (closed volumetric shape). |
| Geometry type | The geometry keyword, such as MESHGEOM, followed by coordinate data enclosed in parentheses. |
Examples
The following examples use the MESHGEOM geometry type.
EWKT with SRID only:
SRID=4326;MESHGEOM(PATCH(INDEXSURFACE M(VERTEX(0 0 1,0 10 2,10 10 3,10 0 4), INDEX((0,1,2),(1,2,3)))))EWKT with SRID and SOLID flag:
SRID=4326;SOLID=true;MESHGEOM(PATCH(INDEXSURFACE M(VERTEX(0 0 1,0 10 2,10 10 3,10 0 4), INDEX((0,1,2),(1,2,3)))))该文章对您有帮助吗？