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// Test subtleties of batchSize and limit.
var t = db.jstests_batch_size;
t.drop();
for (var i = 0; i < 4; i++) {
t.save({_id: i, a: i});
}
function runIndexedTests() {
// With limit, indexed.
assert.eq(2, t.find().limit(2).itcount(), 'G');
assert.eq(2, t.find().sort({a: 1}).limit(2).itcount(), 'H');
// With batchSize, indexed.
// SERVER-12438: If there is an index that provides the sort,
// then a plan with an unindexed sort should never be used.
// Consequently, batchSize will NOT be a hard limit in this case.
// WARNING: the behavior described above may change in the future.
assert.eq(4, t.find().batchSize(2).itcount(), 'I');
assert.eq(4, t.find().sort({a: 1}).batchSize(2).itcount(), 'J');
}
// Without batch size or limit, unindexed.
assert.eq(4, t.find().itcount(), 'A');
assert.eq(4, t.find().sort({a: 1}).itcount(), 'B');
// With limit, unindexed.
assert.eq(2, t.find().limit(2).itcount(), 'C');
assert.eq(2, t.find().sort({a: 1}).limit(2).itcount(), 'D');
// With batchSize, unindexed.
// SERVER-12438: in general batch size does not mean a hard
// limit. With an unindexed sort, however, the server interprets
// batch size as a hard limit so that it can do a top k sort.
// WARNING: this behavior may change in the future.
assert.eq(4, t.find().batchSize(2).itcount(), 'E');
assert.eq(2, t.find().sort({a: 1}).batchSize(2).itcount(), 'F');
// Run the tests with the index twice in order to double check plan caching.
t.ensureIndex({a: 1});
for (var i = 0; i < 2; i++) {
runIndexedTests();
}
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