sortedSetUnionCard

src/database/mongo/sorted.js

@@ -474,6 +474,26 @@ module.exports = function(db, module) {
 		});
 	};
 
+	module.sortedSetUnionCard = function(keys, callback) {
+		if (!Array.isArray(keys) || !keys.length) {
+			return callback(null, 0);
+		}
+
+		var pipeline = [
+			{ $match: { _key: {$in: keys} } },
+			{ $group: { _id: {value: '$value' } } },
+			{ $group: { _id: null,  count: { $sum: 1 } } }
+		];
+
+		var project = { _id: 0, count: '$count' };
+		pipeline.push({	$project: project });
+
+		db.collection('objects').aggregate(pipeline, function(err, data) {
+			console.log(data);
+			callback(err, Array.isArray(data) && data.length ? data[0].count : 0);
+		});
+	};
+
 	module.getSortedSetUnion = function(params, callback) {
 		params.sort = 1;
 		getSortedSetUnion(params, callback);
@@ -484,7 +504,6 @@ module.exports = function(db, module) {
 		getSortedSetUnion(params, callback);
 	};
 
-
 	function getSortedSetUnion(params, callback) {
 		if (!Array.isArray(params.sets) || !params.sets.length) {
 			return callback();

src/database/redis/sorted.js

@@ -232,6 +232,23 @@ module.exports = function(redisClient, module) {
 		multi.exec(callback);
 	};
 
+
+	module.sortedSetUnionCard = function(keys, callback) {
+		var tempSetName = 'temp_' + Date.now();
+
+		var multi = redisClient.multi();
+		multi.zunionstore([tempSetName, keys.length].concat(keys));
+		multi.zcard(tempSetName);
+		multi.del(tempSetName);
+		multi.exec(function(err, results) {
+			if (err) {
+				return callback(err);
+			}
+
+			callback(null, Array.isArray(results) && results.length ? results[1] : 0);
+		});
+	};
+
 	module.getSortedSetUnion = function(params, callback) {
 		params.method = 'zrange';
 		sortedSetUnion(params, callback);

tests/database/sorted.js

@@ -436,6 +436,16 @@ describe('Sorted Set methods', function() {
 		});
 	});
 
+	describe('sortedSetUnionCard', function() {
+		it('should return the number of elements in the union', function(done) {
+			db.sortedSetUnionCard(['sortedSetTest2', 'sortedSetTest3'], function(err, count) {
+				assert.ifError(err);
+				assert.equal(count, 3);
+				done();
+			});
+		});
+	});
+
 	describe('getSortedSetUnion()', function() {
 		it('should return an array of values from both sorted sets sorted by scores lowest to highest', function(done) {
 			db.getSortedSetUnion({sets: ['sortedSetTest2', 'sortedSetTest3'], start: 0, stop: -1}, function(err, values) {