Aggregation: Style improvements

lib/cartodb/backends/cluster.js

@@ -6,7 +6,7 @@ const debug = require('debug')('backend:cluster');
 const AggregationMapConfig = require('../models/aggregation/aggregation-mapconfig');
 
 const windshaftUtils = require('windshaft').utils;
-const wmh = new windshaftUtils.WebMercatorHelper();
+const webmercator = new windshaftUtils.WebMercatorHelper();
 
 module.exports = class ClusterBackend {
     getClusterFeatures (mapConfigProvider, params, callback) {
@@ -159,8 +159,8 @@ const clusterFeaturesQuery = ctx => `
 `;
 
 const gridResolution = ctx => {
-    const zoom_resolution = wmh.getResolution({ z : Math.min(38, ctx.zoom) });
-    return `${256/ctx.res} * (${zoom_resolution})::double precision`;
+    const zoomResolution = webmercator.getResolution({ z : Math.min(38, ctx.zoom) });
+    return `${256/ctx.res} * (${zoomResolution})::double precision`;
 };
 
 const aggregationQuery = ctx => `

lib/cartodb/models/aggregation/aggregation-query.js

@@ -3,6 +3,8 @@
 const timeDimension = require('./time-dimension');
 
 const DEFAULT_PLACEMENT = 'point-sample';
+const windshaftUtils = require('windshaft').utils;
+const webmercator = new windshaftUtils.WebMercatorHelper();
 
 function optionsToParams (options) {
     return {
@@ -265,16 +267,18 @@ const havingClause = ctx => {
 // We limit the the minimum resolution to avoid division by zero problems. The limit used is
 // the pixel size of zoom level 30 (i.e. 1/2*(30+8) of the full earth web-mercator extent), which is about 0.15 mm.
 //
-// NOTE: We'd rather use !scale_denominator!, but in Mapnik this value is extent / 256 for raster
+// NOTE: We'd rather use !pixel_width!, but in Mapnik this value is extent / 256 for raster
 // and extent / tile_extent {4096 default} for MVT, so since aggregations are always based
 // on 256 we can't have the same query in both cases
 // As this scale change doesn't happen in !scale_denominator! we use that instead
+// NOTE 2: The 0.00028 is used in Mapnik (and replicated in pg-mvt) and comes from
+// OGC's Styled Layer Descriptor Implementation Specification
 const gridResolution = ctx => {
-    const minimumResolution = 2*Math.PI*6378137/Math.pow(2,38);
+    const minimumResolution = webmercator.getResolution({ z : 38 });
     return `${256/ctx.res} * GREATEST(!scale_denominator! * 0.00028, ${minimumResolution})::double precision`;
 };
 
-// SQL query to extra the boundaries of the area to be aggregated and the grid resolution
+// SQL query to extract the boundaries of the area to be aggregated and the grid resolution
 // cdb_{x-y}{min_max} return the limits of the tile. Aggregations do [min, max) in both axis
 // cdb_res: Aggregation resolution (as specified by gridResolution)
 // cdb_point_bbox: Tile bounding box [min, max]
@@ -311,17 +315,17 @@ const aggregatedPointWebMercator = (ctx) => {
     switch (ctx.placement) {
 
         // For centroid, we return the average of the cell
-        case `centroid`:
-            return `, ST_SetSRID(ST_MakePoint(AVG(cdb_x), AVG(cdb_y)), 3857) AS the_geom_webmercator`;
+        case 'centroid':
+            return ', ST_SetSRID(ST_MakePoint(AVG(cdb_x), AVG(cdb_y)), 3857) AS the_geom_webmercator';
 
         // Middle point of the cell
-        case `point-grid`:
+        case 'point-grid':
             return `, ST_SetSRID(ST_MakePoint(cdb_pos_grid_x, cdb_pos_grid_y), 3857) AS the_geom_webmercator`;
 
         // For point-sample we'll get a single point directly from the source
         // If it's default aggregation we'll add the extra columns to keep backwards compatibility
-        case `point-sample`:
-            return ``;
+        case 'point-sample':
+            return '';
 
         default:
             throw new Error(`Invalid aggregation placement "${ctx.placement}`);
@@ -332,16 +336,17 @@ const aggregatedPointWebMercator = (ctx) => {
 const aggregatedPointJoin = (ctx) => {
     switch (ctx.placement) {
 
-        case `centroid`:
-            return ``;
+        case 'centroid':
+            return '';
 
-        case `point-grid`:
-            return ``;
+        case 'point-grid':
+            return '';
 
         // For point-sample we'll get a single point directly from the source
         // If it's default aggregation we'll add the extra columns to keep backwards compatibility
-        case `point-sample`:
-            return `NATURAL JOIN
+        case 'point-sample':
+            return `
+NATURAL JOIN
 (
     SELECT ${ctx.isDefaultAggregation ? `*` : `cartodb_id, the_geom_webmercator`}
     FROM
@@ -352,7 +357,7 @@ const aggregatedPointJoin = (ctx) => {
 `;
 
         default:
-            throw new Error(`Invalid aggregation placement "${ctx.placement}`);
+            throw new Error('Invalid aggregation placement "${ctx.placement}"');
     }
 };
 

test/acceptance/aggregation.js

@@ -7,7 +7,7 @@ const TestClient = require('../support/test-client');
 const serverOptions = require('../../lib/cartodb/server_options');
 
 const windshaftUtils = require('windshaft').utils;
-const wmh = new windshaftUtils.WebMercatorHelper();
+const webmercator = new windshaftUtils.WebMercatorHelper();
 
 const suites = [
     {
@@ -112,15 +112,15 @@ describe('aggregation', function () {
     WITH hgrid AS (
         SELECT
             CDB_RectangleGrid (
-                ST_Expand(!bbox!, ${wmh.getResolution({ z : 1 })} * 12),
-                ${wmh.getResolution({ z : 1 })} * 12,
-                ${wmh.getResolution({ z : 1 })} * 12
+                ST_Expand(!bbox!, ${webmercator.getResolution({ z : 1 })} * 12),
+                ${webmercator.getResolution({ z : 1 })} * 12,
+                ${webmercator.getResolution({ z : 1 })} * 12
             ) as cell
     )
     SELECT
         hgrid.cell as the_geom_webmercator,
         count(1) as agg_value,
-        count(1) /power( 12 * ${wmh.getResolution({ z : 1 })}, 2 ) as agg_value_density,
+        count(1) /power( 12 * ${webmercator.getResolution({ z : 1 })}, 2 ) as agg_value_density,
         row_number() over () as cartodb_id
     FROM hgrid, (<%= sql %>) i
     WHERE ST_Intersects(i.the_geom_webmercator, hgrid.cell) GROUP BY hgrid.cell
@@ -207,7 +207,7 @@ describe('aggregation', function () {
     //
     const POINTS_SQL_GRID = (z, resolution) => `
         WITH params AS (
-            SELECT ${wmh.getResolution({ z : z })}*${resolution} AS l -- cell size for Z, resolution
+            SELECT ${webmercator.getResolution({ z : z })}*${resolution} AS l -- cell size for Z, resolution
         )
         SELECT
             row_number() OVER () AS cartodb_id,