Spatial queries with Apache Drill
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README.md

drill-gis

Build Status

drill-gis is a plugin for Apache Drill that supports spatial queries in a way similar to Postgres PostGIS extension. I came with the idea during Tugdual Grall's talk on Apache Drill at Apache Big Data. The first prototype was ready the next day after the talk. Currently it is at proposal/proof-of-concept stage (checkout my drill fork with drill-gis at k255/drill).

What is supported:

  • geometries with initial native binary representation (WKB)
  • functions to create geometries ST_Point(lon, lat), ST_GeomFromText(wkt_text)
  • spatial functions ST_DWithin(geom, geom, distance), ST_Within(geom, geom), ST_Distance(geom, geom)
  • function to convert geometry from binary to text ST_AsText(geom)
  • reprojection of coordinates from one spatial reference system to another ST_Transform(geom, srcSRID, tgtSRID) (using Proj4J)

For an overview of spatial functions based on PostGIS you may refer: PostGIS documentation

Status

The first version of drill-gis is now included in Apache Drill distribution!

Recent changes are not yet available in Apache Drill distibution.

Esri Shapefile format plugin is on its way!

Installation

Clone/download the sourcecode and run:

$ mvn clean package

then copy target/drill-gis* jars to drill's jars/3rdparty directory. Also ensure that to copy esri-geometry-api-1.2.1.jar and proj4j-0.1.0.jar in the same place.

You can also build my fork of Apache Drill with drill-gis implemented as a plugin. Then just run

$ mvn clean package -DskipTests

After building the code go to distibution directory and you can start Drill with:

$ bin/drill-embedded

Usage

Sample dataset

There is a sample CSV dataset included, which is a subset of cities of the world dataset for US California state CA-cities.csv (~5k rows). You can copy it to Drill's sample-data directory.

The structure of the CSV is as follows:

country, state_code, city, latitude, longitude

Following examples are based on queries to sample file which is embedded in drill-gis jar file (classpath) i.e.:

select * from cp.`sample-data/CA-cities.csv` limit 5;

but you can also query dataset from filesystem:

select * from dfs.default.`/home/k255/drill/sample-data/CA-cities.csv` limit 5;

You can see the dataset visualized here (can take a while):

Spatial queries

Creating a simple (binary) geometry is as simple as:

select ST_GeomFromText('POINT(-121.895 37.340)') as geom
    from (VALUES(1));

Creating point geometry based on data field:

select *, ST_Point(columns[4], columns[3]) as geom
    from cp.`sample-data/CA-cities.csv` limit 1;

Common use case is to select data within boundary of given polygon:

select columns[2] as city, columns[4] as lon, columns[3] as lat
    from cp.`sample-data/CA-cities.csv`
    where
        ST_Within(
            ST_Point(columns[4], columns[3]),
            ST_GeomFromText(
                'POLYGON((-121.95 37.28, -121.94 37.35, -121.84 37.35, -121.84 37.28, -121.95 37.28))'
                )
            );

which limits rows of our dataset to region near San Jose as shown here:

Rows can be limited also based on distance (decimal degrees in this case) from given geometry:

select * from
    (select columns[2] as location, columns[4] as lon, columns[3] as lat,
        ST_DWithin(ST_Point(-121.895, 37.339), ST_Point(columns[4], columns[3]), 0.1) as isWithin
        from cp.`sample-data/CA-cities.csv`
    )
    where isWithin = true;

In this example rows are filtered based on distance (0.1deg ~= 11km) from San Jose city:

Now it's possible to transform coordinates from one SRID to other known SRID:

select ST_AsText(ST_Point(columns[4], columns[3])) as SRID_4326,
       ST_AsText(
                 ST_Transform(ST_Point(columns[4], columns[3]), 4326, 3857)
                 ) as SRID_3857
    from cp.`sample-data/CA-cities.csv`;

which gives results like:

+-------------------------------+-----------------------------------------------+
|         SRID_4326             |                 SRID_3857                     |
+-------------------------------+-----------------------------------------------+
| POINT (-118.888019 34.873982) | POINT (-13234553.736501034 4146768.960927167) |
+-------------------------------+-----------------------------------------------+

Author

Karol Potocki

License


Apache 2.0 License