Martin is a PostGIS [Mapbox Vector Tiles](https://github.com/mapbox/vector-tile-spec) server written in Rust using [Actix](https://github.com/actix/actix-web) web framework.
Table Source is a database table wich can be used to query [vector tiles](https://github.com/mapbox/vector-tile-spec). When started, martin will go through all spatial tables in the database and build a list of table sources. A table should have at least one geometry column with non-zero SRID. All other table columns will be represented as a properties of vector tile feature.
Function Source is a database function wich can be used to query [vector tiles](https://github.com/mapbox/vector-tile-spec). When started, martin will look for the functions with a suitable signature. A function that takes `z integer`, `x integer`, `y integer`, and `query_params json` and returns `bytea`, can be used as a Function Source.
**Hint**: You may want to use [TileBBox](https://github.com/mapbox/postgis-vt-util#tilebbox) function to generate bounding-box geometry of the area covered by a tile.
Here is an example of function, that can be used as a Function Source.
```plsql
CREATE OR REPLACE FUNCTION public.function_source(z integer, x integer, y integer, query_params json) RETURNS bytea AS $$
DECLARE
bounds geometry;
mvt bytea;
BEGIN
SELECT INTO bounds TileBBox(z, x, y, 3857);
SELECT INTO mvt ST_AsMVT(tile, 'public.function_source', 4096, 'geom') FROM (
SELECT
ST_AsMVTGeom(geom, bounds, 4096, 64, true) AS geom
FROM public.table_source
WHERE geom && bounds
) as tile WHERE geom IS NOT NULL;
RETURN mvt;
END
$$ LANGUAGE plpgsql IMMUTABLE STRICT PARALLEL SAFE;
If you don't want to expose all of your tables and functions, you can list your sources in configuration file. To start martin with a configuration file, you need to pass a file name with a `--config` argument.
```shell
martin --config config.yaml
```
You can find example configuration file [here](https://github.com/urbica/martin/blob/master/tests/config.yaml).
[Mapbox GL JS](https://github.com/mapbox/mapbox-gl-js) is a JavaScript library for interactive, customizable vector maps on the web. It takes map styles that conform to the
[Mapbox Style Specification](https://www.mapbox.com/mapbox-gl-js/style-spec), applies them to vector tiles that
conform to the [Mapbox Vector Tile Specification](https://github.com/mapbox/vector-tile-spec), and renders them using
WebGL.
You can add a layer to the map and specify martin TileJSON endpoint as a vector source url. You should also specify a `source-layer` property. For Table Sources it is `{schema_name}.{table_name}` by default.
