// Test query stage merge sorting.
t = db.stages_mergesort;
t.drop();

var N = 10;
for (var i = 0; i < N; ++i) {
    t.insert({foo: 1, bar: N - i - 1});
    t.insert({baz: 1, bar: i})
}

t.ensureIndex({foo: 1, bar:1})
t.ensureIndex({baz: 1, bar:1})

// foo == 1
// We would (internally) use "": MinKey and "": MaxKey for the bar index bounds.
ixscan1 = {ixscan: {args:{name: "stages_mergesort", keyPattern:{foo: 1, bar:1},
                          startKey: {"": 1, "": 0},
                          endKey: {"": 1, "": 100000}, endKeyInclusive: true,
                          direction: 1}}};
// baz == 1
ixscan2 = {ixscan: {args:{name: "stages_mergesort", keyPattern:{baz: 1, bar:1},
                          startKey: {"": 1, "": 0},
                          endKey: {"": 1, "": 100000}, endKeyInclusive: true,
                          direction: 1}}};

mergesort = {mergeSort: {args: {nodes: [ixscan1, ixscan2], pattern: {bar: 1}}}};
res = db.runCommand({stageDebug: mergesort});
assert(!db.getLastError());
assert.eq(res.ok, 1);
assert.eq(res.results.length, 2 * N);
assert.eq(res.results[0].bar, 0);
assert.eq(res.results[2 * N - 1].bar, N - 1);