Loading a shapefile into Amazon Redshift - Amazon Redshift
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Loading a shapefile into Amazon Redshift

You can use the COPY command to ingest Esri shapefiles stored in Amazon S3 into Amazon Redshift tables. A shapefile stores the geometric location and attribute information of geographic features in a vector format. The shapefile format can spatially describe spatial objects such as points, lines, and polygons. For more information about a shapefile, see Shapefile in Wikipedia.

The COPY command supports the data format parameter SHAPEFILE. By default, the first column of the shapefile is either a GEOMETRY or IDENTITY column. All subsequent columns follow the order specified in the shapefile. However, the target table doesn't need to be in this exact layout because you can use COPY column mapping to define the order. For information about the COPY command shapefile support, see SHAPEFILE.

In some cases, the resulting geometry size might be greater than the maximum for storing a geometry in Amazon Redshift. If so, you can use the COPY option SIMPLIFY or SIMPLIFY AUTO to simplify the geometries during ingestion as follows:

  • Specify SIMPLIFY tolerance to simplify all geometries during ingestion using the Ramer-Douglas-Peucker algorithm and the given tolerance.

  • Specify SIMPLIFY AUTO without tolerance to simplify only geometries that are larger than the maximum size using the Ramer-Douglas-Peucker algorithm. This approach calculates the minimum tolerance that is large enough to store the object within the maximum size limit.

  • Specify SIMPLIFY AUTO max_tolerance to simplify only geometries that are larger than the maximum size using the Ramer-Douglas-Peucker algorithm and the automatically calculated tolerance. This approach makes sure that the tolerance doesn't exceed the maximum tolerance.

For information about the maximum size of a GEOMETRY data value, see Considerations when using spatial data with Amazon Redshift.

In some cases, the tolerance is low enough that the record can't shrink below the maximum size of a GEOMETRY data value. In these cases, you can use the MAXERROR option of the COPY command to ignore all or up to a certain number of ingestion errors.

The COPY command also supports loading GZIP shapefiles. To do this, specify the COPY GZIP parameter. With this option, all shapefile components must be independently compressed and share the same compression suffix.

If a projection description file (.prj) exists with the shapefile, Redshift uses it to determine the spatial reference system id (SRID). If the SRID is valid, the resulting geometry has this SRID assigned. If the SRID value associated with the input geometry does not exist, the resulting geometry has the SRID value zero. You can disable automatic detection of the spatial reference system id at the session level by using SET read_srid_on_shapefile_ingestion to OFF.

Query the SYS_SPATIAL_SIMPLIFY or SVL_SPATIAL_SIMPLIFY system views to view which records have been simplified, along with the calculated tolerance. When you specify SIMPLIFY tolerance, this view contains a record for each COPY operation. Otherwise, it contains a record for each simplified geometry. For more information, see SYS_SPATIAL_SIMPLIFY or SVL_SPATIAL_SIMPLIFY.

For examples of loading a shapefile, see Loading a shapefile into Amazon Redshift.