SERVER-14306 Make sure mongos never requests more results than needed from the shards

1 files changed, 45 insertions, 0 deletions

diff --git a/jstests/sharding/in_memory_sort_limit.js b/jstests/sharding/in_memory_sort_limit.js
new file mode 100644
index 00000000000..c1eeeddfde5
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+++ b/jstests/sharding/in_memory_sort_limit.js
@@ -0,0 +1,45 @@
+// Test SERVER-14306.  Do a query directly against a mongod with an in-memory sort and a limit that
+// doesn't cause the in-memory sort limit to be reached, then make sure the same limit also doesn't
+// cause the in-memory sort limit to be reached when running through a mongos.
+(function() {
+     "use strict";
+
+     var st = new ShardingTest({ shards: 2, chunkSize: 1, other: {separateConfig: true}});
+     var db = st.s.getDB('test');
+     var mongosCol = db.getCollection('skip');
+     db.adminCommand({ enableSharding: 'test' });
+     db.adminCommand({ shardCollection: 'test.skip', key: { _id: 1 }});
+     // Disable balancing of this collection
+     assert.writeOK(db.getSiblingDB('config').collections.update({_id: 'test.skip'},
+                                                                 {$set: {noBalance: true}}));
+
+
+     var filler = new Array(10000).toString();
+     var bulk = [];
+     // create enough data to exceed 32MB in-memory sort limit.
+     for (var i = 0; i < 20000; i++) {
+         bulk.push({x:i, str:filler});
+     }
+     assert.writeOK(mongosCol.insert(bulk));
+     // Make sure that at least 1 doc is on another shard so that mongos doesn't treat this as a
+     // single-shard query (which doesn't exercise the bug)
+     assert.commandWorked(db.getSiblingDB('admin').runCommand({moveChunk: 'test.skip',
+                                                               find: {_id:1},
+                                                               to: 'shard0001'}));
+
+     var docCount = mongosCol.count();
+     var shardCol = st.shard0.getDB('test').getCollection('skip');
+     var passLimit = 2000;
+     var failLimit = 4000;
+     jsTestLog("Test no error with limit of " + passLimit + " on mongod");
+     assert.eq(passLimit, shardCol.find().sort({x:1}).limit(passLimit).itcount());
+
+     jsTestLog("Test error with limit of " + failLimit + " on mongod");
+     assert.throws( function() {shardCol.find().sort({x:1}).limit(failLimit).itcount(); } );
+
+     jsTestLog("Test no error with limit of " + passLimit + " on mongos");
+     assert.eq(passLimit, mongosCol.find().sort({x:1}).limit(passLimit).itcount());
+
+     jsTestLog("Test error with limit of " + failLimit + " on mongos");
+     assert.throws( function() {mongosCol.find().sort({x:1}).limit(failLimit).itcount(); } );
+ })();
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