isabella232 / tilelive-pgquery

PostgreSQL tilelive tile generator that runs an MVT-returning query

tilelive-pgquery

This tilelive module runs a PostgreSQL query created by the OpenMapTiles MVT tools, and returns the data blob from the query results.

This module can connect to more than one postgreSQL server and load-balance requests based on the number of pending queries, weighted by the maxpool param.

This module expects either a parametrized query, or the name of a PostgreSQL function with three parameters: z, x, y. The result is expected to be zero or one row, with the first column being the tile data blob. If the key parameter is set, the second column must be the hash of the content. If the result blob is empty, or there are no rows, pgquery raises the standard "no-tile" error.

Parameters

• database (string, required) - PostgreSQL database name. Uses PGDATABASE env var if not set.
• host (string, required) - PostgreSQL host. Could be used multiple times for load balancing. Uses PGHOST env var if not set.
• port (integer) - PostgreSQL port. Could be used multiple times for load balancing. If given, must be used once or the same number of times as there are hosts. Uses PGPORT env var if not set.
• username (string) - PostgreSQL username. Uses PGUSER env var if not set.
• password (string) - PostgreSQL password. Uses PGPASSWORD env var if not set.
• maxpool (integer) - size of the connection pool (default=10). If given, must be used once or the same number of times as there are hosts.
• minzoom (zoom) - minimum allowed zoom (default=0)
• maxzoom (zoom) - maximum allowed zoom (default=22)
• testOnStartup (tile index) - set which tile (in z/x/y or z,x,y format) to get on startup to verify database connection. To disable, set to an empty value. By default uses a simple tile in Norway on zoom 10.
• serverInfo (boolean) - if non-empty or not given, prints PostgreSQL & PostGIS version data and key metrics. To disable, set to an empty value.
• prepareStatement (boolean) - use prepared statements (defaults to false for funcZXY and query, true for queryFile).
• resolveDns (boolean) - convert host value(s) to corresponding IPs on startup. If DNS resolves to multiple IPs, all IPs will be used in a pool.
• errorsAsEmpty (boolean) - if set, treats all query errors as empty tiles, returning standard Tile does not exist error.
• connectionInitQuery (string) - if set, run this query each time a new connection is made to a server.
• name (string) - if set, adds this name to the metadata's name field
• key (boolean) - if set, assumes the second query result column is a key that should be attached to the result buffer.
• nogzip (boolean) - do not compress data blob (use this if the query returns compressed data or an image)
• contentType (string) - set content-type header. Uses application/x-protobuf by default.
• contentEncoding (string) - set content-encoding header. Uses gzip by default.

Exactly one of the following 3 parameters must be given.

• funcZXY (string) - name of the function that accepts the Z, X, Y int parameters.
• query (string) - an SQL statement that uses $1, $2, $3 parameters for Z, X, Y.
• queryFile (string) - filename of a file that contains the query with $1, $2, $3 parameters for Z, X, Y.

Testing

Testing requires a local PostgreSQL service, even if it is empty and runs inside a docker container:

docker run -it --rm --name pg-docker -e POSTGRES_PASSWORD=openmaptiles -e POSTGRES_USER=openmaptiles -e POSTGRES_DB=openmaptiles -p 5432:5432 postgres

# For multi-host test, run another instance on a different port
docker run -it --rm --name pg-docker2 -e POSTGRES_PASSWORD=openmaptiles -e POSTGRES_USER=openmaptiles -e POSTGRES_DB=openmaptiles -p 5433:5432 postgres

Run tests in a separate shell using npm run test