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