tilelive-postgis

Implements the tilelive API for generating mapnik vector tiles from PostGIS.

Installation

npm install @mapbox/tilelive tilelive-postgis

Usage

const tilelive = require('@mapbox/tilelive');
require('tilelive-postgis').registerProtocols(tilelive);

const uri = 'postgis://user:password@localhost:5432/test?table=test_table&geometry_field=geometry&srid=4326';
tilelive.load(uri, (error, source) => {
  if (error) throw error;

  source.getTile(0, 0, 0, (error, tile, headers) => {
    // `error` is an error object when generation failed, otherwise null.
    // `tile` contains the compressed image file as a Buffer
    // `headers` is a hash with HTTP headers for the image.
  });
});

If PostgreSQL server running locally and accepting connections on Unix domain socket, you can connect like this:

const uri = 'postgis:///var/run/postgresql/test?table=test&geometry_field=geom';
tilelive.load(uri, (error, source) => { ... });

You can also use query parameter to specify sub-query like this:

const query = `(select * from schemaName.tableName where st_intersects(geometry, !bbox!)) as query`;
const uri = `postgis://user@localhost/test?table=test_table&geometry_field=geometry&query=${encodeURI(query)}`;
tilelive.load(uri, (error, source) => { ... });

Parameters

The only parameter that is not mapnik specific is:

| parameter | value | description | default | |:------------------|----------|---------------|----------:| | layerName | string | name of the layer in resulting tiles. | defaults to the table name for backwards compatibility.|

Actual list of parameters you can see here.

| parameter | value | description | default | |:------------------|----------|---------------|----------:| | table | string | name of the table to fetch. | | | geometry_field | string | name of the geometry field, in case you have more than one in a single table. This field and the SRID will be deduced from the query in most cases, but may need to be manually specified in some cases.| | | geometry_table | string | name of the table containing the returned geometry; for determining RIDs with subselects | | | srid | integer | srid of the table, if this is > 0 then fetching data will avoid an extra database query for knowing the srid of the table | 0 | | extent | string | maxextent of the geometries | determined by querying the metadata for the table | | extent_from_subquery | boolean | evaluate the extent of the subquery, this might be a performance issue | false | | connect_timeout | integer | timeout is seconds for the connection to take place | 4 | | persist_connection | boolean | choose whether to share the same connection for subsequent queries | true | | row_limit | integer | max number of rows to return when querying data, 0 means no limit | 0 | | cursor_size | integer | if this is > 0 then server cursor will be used, and will prefetch this number of features | 0 | | initial_size | integer | initial size of the stateless connection pool | 1 | | max_size | integer | max size of the stateless connection pool | 10 | | multiple_geometries | boolean | whether to use multiple different objects or a single one when dealing with multi-objects (this is mainly related to how the label are used in the map, one label for a multi-polygon or one label for each polygon of a multi-polygon)| false | | encoding | string | internal file encoding | utf-8 | | simplify_geometries | boolean | whether to automatically reduce input vertices. Only effective when output projection matches (or is similar to) input projection. Available from version 2.1.x up. | false | | max_async_connection | integer | max number of PostGIS queries for rendering one map in asynchronous mode. Default value (1) has no effect. | 1 |