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Type:
Task
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Resolution: Done
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Priority:
Major - P3
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Affects Version/s: None
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Component/s: manual
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Labels:None
queries on sharded collections run against primary can be covered. Behavior seems to have changed starting 2.6.4.
mongos limitation seem unchanged (until 2.8)
MongoDB shell version: 2.6.3
connecting to: 127.0.0.1:27018/test
shardA:PRIMARY> db.foo.find( { a: 1 }, { _id: 0 } ).explain()
{
"cursor" : "BtreeCursor a_1",
"isMultiKey" : false,
"n" : 1,
"nscannedObjects" : 1,
"nscanned" : 1,
"nscannedObjectsAllPlans" : 1,
"nscannedAllPlans" : 1,
"scanAndOrder" : false,
"indexOnly" : false,
sharda-265:PRIMARY> db.foo.find( { a: 1}, { a: 1, _id: 0 } ).explain()
{
"cursor" : "BtreeCursor a_1_b_1",
"isMultiKey" : false,
"n" : 1,
"nscannedObjects" : 0,
"nscanned" : 1,
"nscannedObjectsAllPlans" : 0,
"nscannedAllPlans" : 2,
"scanAndOrder" : false,
"indexOnly" : true,
