Why is postgis awesome?
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PostGIS is an open-source extension for SQL that addresses challenges in spatial data storage and querying by providing custom spatial data types and spatial operators for geometry manipulations. It integrates spatial indexes like R-trees for fast querying, improving performance for geospatial analysis. PostGIS follows the OGC's Simple Features for SQL specification, enhancing SQL capabilities with lightweight geometries and optimized indexes.
![These three solutions are integrated
in PostGIS
- Geometry types for Points, LineStrings, Polygons, MultiPoints, MultiLineStrings, MultipPolygons and
GeometryCollections.
- Spatial predicates for determining the interactions of geometries using the 3x3 DE-9IM (provided by the GEOS
software library).
- Spatial operators for determining geospatial measurements like area, distance, length and perimeter.
- Spatial operators for determining geospatial set operations, like union, difference, symmetric difference and
buffers (provided by GEOS).
- R-tree-over-GiST (Generalized Search Tree) spatial indexes for high speed spatial querying.
- Index selectivity support, to provide high performance query plans for mixed spatial/non-spatial queries.
- For raster data, PostGIS WKT Raster (now integrated into PostGIS 2.0+ and renamed PostGIS Raster)
- The PostGIS implementation is based on "light-weight" geometries and indexes optimized to reduce disk and
memory footprint. Using light-weight geometries helps servers increase the amount of data migrated up from
physical disk storage into RAM, improving query performance substantially.
- PostGIS is registered as "implements the specified standard" for "Simple Features for SQL" by the OGC.[2]
PostGIS has not been certified as compliant by the OGC. For the OGC's definition of compliant, see What does
"Compliant" mean?.
Source: wikipedia](https://image.slidesharecdn.com/presentatiepostgis-161118080844/85/Why-is-postgis-awesome-16-320.jpg)
Why is postgis awesome?
- 1. Why is PostGIS awesome? Reason 1: it is open source Kasper Van Lombeek - Forespell.com 17 / 11 / 2016 - DS Meetup Antwerp
- 2. First we need to understand: Why did SQL need an extension?
- 3. Problem 1: data storage
- 4. Try to store this rectangle in a db A db that allows only atomic data points. P1 P2 P3P4
- 5. Lets tryPid X Y P1 0 0 P2 0 1 P3 1 1 P4 1 0 Table 1: points Eid Pid E1 P1 E1 P2 E2 P2 E2 … P3 … Table 3: Starts_or_ends Eid Length E1 1 E2 1 E3 1 E4 1 Table 2: Edges P1 P2 P3P4 E1 E2 E3 E4 Rid Eid R1 E1 R1 E2 R1 E3 R1 … E4 … Table 4: Boundary Rid Rname R1 UnitSquare Table 5: Rectangle
- 6. Lets try storing all the neighbourhoods in Belgium?
- 7. Solution: SQL 3 custom spatial data types PostGIS follows the Simple Features for SQL specification from the Open Geospatial Consortium (OGC).
- 8. Problem 2: querying the database
- 9. How to query our db? Describe in words how to query the points within the rectangle.
- 10. What about a more complex shape? Would your query still work?
- 11. Solution: spatial operators Provided by GEOS - Geometry Engine, Open Source
- 12. Problem 3: querying the database fast
- 13. In which area do we have most bicycle thefts?
- 14. Need for an index
- 15. Solution: spatial index R-tree implementation of bounding boxes of geometries
- 16. These three solutions are integrated in PostGIS - Geometry types for Points, LineStrings, Polygons, MultiPoints, MultiLineStrings, MultipPolygons and GeometryCollections. - Spatial predicates for determining the interactions of geometries using the 3x3 DE-9IM (provided by the GEOS software library). - Spatial operators for determining geospatial measurements like area, distance, length and perimeter. - Spatial operators for determining geospatial set operations, like union, difference, symmetric difference and buffers (provided by GEOS). - R-tree-over-GiST (Generalized Search Tree) spatial indexes for high speed spatial querying. - Index selectivity support, to provide high performance query plans for mixed spatial/non-spatial queries. - For raster data, PostGIS WKT Raster (now integrated into PostGIS 2.0+ and renamed PostGIS Raster) - The PostGIS implementation is based on "light-weight" geometries and indexes optimized to reduce disk and memory footprint. Using light-weight geometries helps servers increase the amount of data migrated up from physical disk storage into RAM, improving query performance substantially. - PostGIS is registered as "implements the specified standard" for "Simple Features for SQL" by the OGC.[2] PostGIS has not been certified as compliant by the OGC. For the OGC's definition of compliant, see What does "Compliant" mean?. Source: wikipedia
- 17. Demo in IPython notebook