diff --git a/lib/cartodb/controllers/layergroup.js b/lib/cartodb/controllers/layergroup.js
index 182fcff5..e10a59c5 100644
--- a/lib/cartodb/controllers/layergroup.js
+++ b/lib/cartodb/controllers/layergroup.js
@@ -516,22 +516,28 @@ function getAffectedTables (layergroupAffectedTables, pgConnection) {
             return next();
         }
 
+        const sql = [];
+        mapconfig.getLayers().forEach(function(layer) {
+            sql.push(layer.options.sql);
+            if (layer.options.affected_tables) {
+                layer.options.affected_tables.map(function(table) {
+                    sql.push(`SELECT * FROM ${table} LIMIT 0`);
+                });
+            }
+        });
+
+        const sql = queries.length ? queries.join(';') : null;
+
+        if (!sql) {
+            return next();
+        }
+
         pgConnection.getConnection(user, (err, connection) => {
             if (err) {
                 global.logger.warn('ERROR generating cache channel:', err);
                 return next();
             }
 
-            const sql = [];
-            mapconfig.getLayers().forEach(function(layer) {
-                sql.push(layer.options.sql);
-                if (layer.options.affected_tables) {
-                    layer.options.affected_tables.map(function(table) {
-                        sql.push(`SELECT * FROM ${table} LIMIT 0`);
-                    });
-                }
-            });
-
             QueryTables.getAffectedTablesFromQuery(connection, sql.join(';'), (err, affectedTables) => {
                 req.profiler.done('getAffectedTablesFromQuery');
                 if (err) {