tilelive-postgis

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

Installation

npm install tilelive-postgis

Usage

const tilelive = require('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 erroror 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

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. Full doc here. Default value (1) has no effect.	1