diff --git a/lib/cartodb/backends/layer-stats/mapnik-layer-stats.js b/lib/cartodb/backends/layer-stats/mapnik-layer-stats.js
index dc49691a..d8b01837 100644
--- a/lib/cartodb/backends/layer-stats/mapnik-layer-stats.js
+++ b/lib/cartodb/backends/layer-stats/mapnik-layer-stats.js
@@ -141,14 +141,26 @@ function _sample(ctx) {
     return queryUtils.queryPromise(ctx.dbConnection, sqlMaxMin)
         .then(maxMinRes => {
             const { min_id: min, id_span: span } = maxMinRes.rows[0];
-            const ids = queryUtils.getSampleValuesFromRange(min, span, limit);
-            const sqlSample = _getSQL(ctx, sql => queryUtils.getSampleFromIdsQuery(sql, ids, columns));
+            const values = _getSampleValuesFromRange(min, span, limit);
+            const sqlSample = _getSQL(ctx, sql => queryUtils.getSampleFromIdsQuery(sql, values, columns));
 
             return queryUtils.queryPromise(ctx.dbConnection, sqlSample);
         })
         .then(res => ({ sample: res.rows }));
 }
 
+function _getSampleValuesFromRange (min, span, limit) {
+    const sample = new Set();
+
+    limit = limit < span ? limit : span;
+
+    while (sample.size < limit) {
+        sample.add(Math.floor(min + Math.random() * span));
+    }
+
+    return Array.from(sample);
+}
+
 function _columnsMetadataRequired(options) {
     // We need determine the columns of a query
     // if either column stats or dimension stats are required,
diff --git a/lib/cartodb/utils/query-utils.js b/lib/cartodb/utils/query-utils.js
index 63d66110..b6e6d6bc 100644
--- a/lib/cartodb/utils/query-utils.js
+++ b/lib/cartodb/utils/query-utils.js
@@ -160,18 +160,6 @@ module.exports.getMaxMinColumnQuery = function (query, column = 'cartodb_id') {
     `;
 };
 
-module.exports.getSampleValuesFromRange = function getSampleValuesFromRange (min, span, limit) {
-    const sample = new Set();
-
-    limit = limit < span ? limit : span;
-
-    while (sample.size < limit) {
-        sample.add(Math.floor(min + Math.random() * span));
-    }
-
-    return Array.from(sample);
-};
-
 module.exports.getSampleFromIdsQuery = function (query, ids, columns, column = 'cartodb_id') {
     return `
         SELECT