create tileserver

[brandonfcohen1]

sample:

app.get("/api/v1/demovector/:x/:y/:z/:t?", function(req, res) {
  let bbox = mercator.bbox(req.params.x, req.params.y, req.params.z)
  const sql = `
      SELECT ST_AsMVT(q, 'demographics', 4096, 'geom')
      FROM (
          SELECT
              key,
              ST_ASText(geom) w,
              ST_AsMVTGeom(
                  geom,
                  ST_MakeBox2D(ST_Point(${bbox[0]}, ${bbox[1]}), ST_Point(${bbox[2]}, ${bbox[3]})), 4096,
                  256,
                  true
              ) geom
          FROM (select * from `+req.params.t+` WHERE ST_Intersects(geom, 
                  ST_MakeEnvelope($1, $2, $3, $4, $5))) r        
      ) as q`

  const values = [bbox[0], bbox[1], bbox[2], bbox[3], 4326]
  app.pgpool.query(sql, values , function(err, mvt) {
      if (err) {
          console.log(err)
      } else {
          res.setHeader('Content-Type', 'application/x-protobuf')
          res.send(mvt.rows[0].st_asmvt)
      }
  })
})