path: root/jstests/sharding/aggregates_during_balancing.js

// Inserts some interesting data into a sharded collection, enables the balancer, and tests that
// various kinds of aggregations return the expected results.
(function() {
load('jstests/aggregation/extras/utils.js');

var shardedAggTest =
    new ShardingTest({shards: 2, mongos: 1, other: {chunkSize: 1, enableBalancer: true}});

shardedAggTest.adminCommand({enablesharding: "aggShard"});
db = shardedAggTest.getDB("aggShard");
shardedAggTest.ensurePrimaryShard('aggShard', shardedAggTest.shard0.shardName);

db.ts1.drop();
db.literal.drop();

shardedAggTest.adminCommand({shardcollection: "aggShard.ts1", key: {"_id": 1}});
shardedAggTest.adminCommand({shardcollection: "aggShard.literal", key: {"_id": 1}});

/*
Test combining results in mongos for operations that sub-aggregate on shards.

The unusual operators here are $avg, $pushToSet, $push.   In the case of $avg,
the shard pipeline produces an object with the current subtotal and item count
so that these can be combined in mongos by totalling the subtotals counts
before performing the final division.  For $pushToSet and $push, the shard
pipelines produce arrays, but in mongos these are combined rather than simply
being added as arrays within arrays.
*/

var count = 0;
var strings = [
    "one",     "two",     "three",     "four",     "five",     "six",      "seven",
    "eight",   "nine",    "ten",       "eleven",   "twelve",   "thirteen", "fourteen",
    "fifteen", "sixteen", "seventeen", "eighteen", "nineteen", "twenty"
];

jsTestLog("Bulk inserting data");
var nItems = 200000;
var bulk = db.ts1.initializeUnorderedBulkOp();
for (i = 0; i < nItems; ++i) {
    bulk.insert({
        _id: i,
        counter: ++count,
        number: strings[i % 20],
        random: Math.random(),
        filler: "0123456789012345678901234567890123456789"
    });
}
assert.commandWorked(bulk.execute());

jsTestLog('a project and group in shards, result combined in mongos');
var a1 = db.ts1
             .aggregate([
                 {$project: {cMod10: {$mod: ["$counter", 10]}, number: 1, counter: 1}},
                 {
                     $group: {
                         _id: "$cMod10",
                         numberSet: {$addToSet: "$number"},
                         avgCounter: {$avg: "$cMod10"}
                     }
                 },
                 {$sort: {_id: 1}}
             ])
             .toArray();

for (i = 0; i < 10; ++i) {
    assert.eq(a1[i].avgCounter, a1[i]._id, 'agg sharded test avgCounter failed');
    assert.eq(a1[i].numberSet.length, 2, 'agg sharded test numberSet length failed');
}

jsTestLog('an initial group starts the group in the shards, and combines them in mongos');
var a2 = db.ts1.aggregate([{$group: {_id: "all", total: {$sum: "$counter"}}}]).toArray();

jsTestLog('sum of an arithmetic progression S(n) = (n/2)(a(1) + a(n));');
assert.eq(a2[0].total, (nItems / 2) * (1 + nItems), 'agg sharded test counter sum failed');

jsTestLog('A group combining all documents into one, averaging a null field.');
assert.eq(db.ts1.aggregate([{$group: {_id: null, avg: {$avg: "$missing"}}}]).toArray(),
          [{_id: null, avg: null}]);

jsTestLog('an initial group starts the group in the shards, and combines them in mongos');
var a3 =
    db.ts1.aggregate([{$group: {_id: "$number", total: {$sum: 1}}}, {$sort: {_id: 1}}]).toArray();

for (i = 0; i < strings.length; ++i) {
    assert.eq(a3[i].total, nItems / strings.length, 'agg sharded test sum numbers failed');
}

jsTestLog('a match takes place in the shards; just returning the results from mongos');
var a4 = db.ts1
             .aggregate([{
                 $match: {
                     $or: [
                         {counter: 55},
                         {counter: 1111},
                         {counter: 2222},
                         {counter: 33333},
                         {counter: 99999},
                         {counter: 55555}
                     ]
                 }
             }])
             .toArray();
assert.eq(a4.length, 6, tojson(a4));
for (i = 0; i < 6; ++i) {
    c = a4[i].counter;
    printjson({c: c});
    assert((c == 55) || (c == 1111) || (c == 2222) || (c == 33333) || (c == 99999) || (c == 55555),
           'agg sharded test simple match failed');
}

function testSkipLimit(ops, expectedCount) {
    jsTestLog('testSkipLimit(' + tojson(ops) + ', ' + expectedCount + ')');
    if (expectedCount > 10) {
        // make shard -> mongos intermediate results less than 16MB
        ops.unshift({$project: {_id: 1}});
    }

    ops.push({$group: {_id: 1, count: {$sum: 1}}});

    var out = db.ts1.aggregate(ops).toArray();
    assert.eq(out[0].count, expectedCount);
}

testSkipLimit([], nItems);  // control
testSkipLimit([{$skip: 10}], nItems - 10);
testSkipLimit([{$limit: 10}], 10);
testSkipLimit([{$skip: 5}, {$limit: 10}], 10);
testSkipLimit([{$limit: 10}, {$skip: 5}], 10 - 5);
testSkipLimit([{$skip: 5}, {$skip: 3}, {$limit: 10}], 10);
testSkipLimit([{$skip: 5}, {$limit: 10}, {$skip: 3}], 10 - 3);
testSkipLimit([{$limit: 10}, {$skip: 5}, {$skip: 3}], 10 - 3 - 5);

// test sort + limit (using random to pull from both shards)
function testSortLimit(limit, direction) {
    jsTestLog('testSortLimit(' + limit + ', ' + direction + ')');
    var from_cursor =
        db.ts1.find({}, {random: 1, _id: 0}).sort({random: direction}).limit(limit).toArray();
    var from_agg =
        db.ts1
            .aggregate(
                [{$project: {random: 1, _id: 0}}, {$sort: {random: direction}}, {$limit: limit}])
            .toArray();
    assert.eq(from_cursor, from_agg);
}
testSortLimit(1, 1);
testSortLimit(1, -1);
testSortLimit(10, 1);
testSortLimit(10, -1);
testSortLimit(100, 1);
testSortLimit(100, -1);

function testAvgStdDev() {
    jsTestLog('testing $avg and $stdDevPop in sharded $group');
    // $stdDevPop can vary slightly between runs if a migration occurs. This is why we use
    // assert.close below.
    var res = db.ts1
                  .aggregate([{
                      $group: {
                          _id: null,
                          avg: {$avg: '$counter'},
                          stdDevPop: {$stdDevPop: '$counter'},
                      }
                  }])
                  .toArray();
    // http://en.wikipedia.org/wiki/Arithmetic_progression#Sum
    var avg = (1 + nItems) / 2;
    assert.close(res[0].avg, avg, '', 10 /*decimal places*/);

    // http://en.wikipedia.org/wiki/Arithmetic_progression#Standard_deviation
    var stdDev = Math.sqrt(((nItems - 1) * (nItems + 1)) / 12);
    assert.close(res[0].stdDevPop, stdDev, '', 10 /*decimal places*/);
}
testAvgStdDev();

function testSample() {
    jsTestLog('testing $sample');
    [0, 1, 10, nItems, nItems + 1].forEach(function(size) {
        // TODO: SERVER-29446 Remove this try catch block after completing SERVER-29446.
        let res = {};
        try {
            res = db.ts1.aggregate([{$sample: {size: size}}]).toArray();
        } catch (e) {
            assert.eq(e.code, 28799, e);
            return;
        }
        assert.eq(res.length, Math.min(nItems, size));
    });
}

testSample();

jsTestLog('test $out by copying source collection verbatim to output');
var outCollection = db.ts1_out;
var res = db.ts1.aggregate([{$out: outCollection.getName()}]).toArray();
assert.eq(db.ts1.find().itcount(), outCollection.find().itcount());
assert.eq(db.ts1.find().sort({_id: 1}).toArray(), outCollection.find().sort({_id: 1}).toArray());

// Make sure we error out if $out collection is sharded
assert.commandFailed(
    db.runCommand({aggregate: outCollection.getName(), pipeline: [{$out: db.ts1.getName()}]}));

assert.commandWorked(db.literal.save({dollar: false}));

result =
    db.literal
        .aggregate([{
            $project: {_id: 0, cost: {$cond: ['$dollar', {$literal: '$1.00'}, {$literal: '$.99'}]}}
        }])
        .toArray();

assert.eq([{cost: '$.99'}], result);

(function() {
jsTestLog('Testing a $match stage on the shard key.');

var outCollection = 'testShardKeyMatchOut';

// Point query.
var targetId = Math.floor(nItems * Math.random());
var pipeline = [{$match: {_id: targetId}}, {$project: {_id: 1}}, {$sort: {_id: 1}}];
var expectedDocs = [{_id: targetId}];
// Normal pipeline.
assert.eq(db.ts1.aggregate(pipeline).toArray(), expectedDocs);
// With $out.
db[outCollection].drop();
pipeline.push({$out: outCollection});
db.ts1.aggregate(pipeline);
assert.eq(db[outCollection].find().toArray(), expectedDocs);

// Range query.
var range = 500;
var targetStart = Math.floor((nItems - range) * Math.random());
pipeline = [
    {$match: {_id: {$gte: targetStart, $lt: targetStart + range}}},
    {$project: {_id: 1}},
    {$sort: {_id: 1}}
];
expectedDocs = [];
for (var i = targetStart; i < targetStart + range; i++) {
    expectedDocs.push({_id: i});
}
// Normal pipeline.
assert.eq(db.ts1.aggregate(pipeline).toArray(), expectedDocs);
// With $out.
db[outCollection].drop();
pipeline.push({$out: outCollection});
db.ts1.aggregate(pipeline);
assert.eq(db[outCollection].find().toArray(), expectedDocs);
}());

shardedAggTest.stop();
}());