gpkg

GeoPackage

This provider connects to GeoPackage databases (See http://www.geopackage.org/ http://www.opengeospatial.org/standards/geopackage)

The connection between tegola and a GeoPackage is configured in a tegola.toml file. An example minimum connection config:

[[providers]]
name = "sample_gpkg"
type = "gpkg"
filepath = "/path/to/my/sample_gpkg.gpkg"

Connection Properties

• name (string): [Required] provider name is referenced from map layers.
• type (string): [Required] the type of data provider. must be "gpkg" to use this data provider.
• filepath (string): [Required] The system file path to the GeoPackage file you wish to connect to.

Provider Layers

In addition to the connection configuration above, Provider Layers need to be configured. A Provider Layer tells tegola how to query a GeoPackage for a certain layer. An example minimum config:

[[providers.layers]]
name = "land_polygons"
tablename = "land_polygons"
id_fieldname = "fid"

Provider Layers Properties

• name (string): [Required] the name of the layer. This is used to reference this layer from map layers.
• tablename (string): [*Required] the name of the database table to query against. Required if sql is not defined.
• id_fieldname (string): [Optional] the name of the feature id field. defaults to fid
• fields ([]string): [Optional] a list of fields (column names) to include as feature tags. Can be used if sql is not defined.
• sql (string): [*Required] custom SQL to use use. Required if tablename is not defined. Supports the following WHERE-clause tokens:
  • !BBOX! - [Required] will be replaced with the bounding box of the tile before the query is sent to the database. To support this token, your custom SQL must do a couple of things.
    • You must join your feature table to the spatial index table: i.e. JOIN feature_table ft rtree_feature_table_geom si ON ft.fid = rt.si
    • Include the following fields in your SELECT clause: si.minx, si.miny, si.maxx, si.maxy
    • Note that the id field for your feature table may be something other than fid
  • !ZOOM! - [Optional] Currently allowed, but does nothing.

*Required: either the tablename or sql must be defined, but not both.

Example minimum custom SQL config

[[providers.layers]]
name = "a_points"
sql = "SELECT fid, geom, amenity, religion, tourism, shop, si.minx, si.miny, si.maxx, si.maxy FROM land_polygons lp JOIN rtree_land_polygons_geom si ON lp.fid = si.id WHERE !BBOX!"