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Type:
Bug
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Resolution: Duplicate
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Priority:
Major - P3
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Affects Version/s: 2.0.5, 2.1.0
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Component/s: Querying
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Environment:tried via mongoshell & java driver 2.6.5/2.8.0rc1 on osx lion (installed via homebrew) & ubuntu 10.10
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ALL
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I can demonstrate the problem using mongoshell commands. First the case which proves the batchsize works when no sort criteria is provided:
Given a collection containing 101 documents
when I issue a query which matches all documents in the collection, using a batchSize which is smaller than number of documents in the collection
and I iterate through the cursor, keeping a count of the number of documents
then the count should match the number of documents in the collection.
> db.test.count()
101
> var cursor = db.test.find().batchSize(100);
> var count = 0;
> while(cursor.hasNext()) { cursor.next(); count++; }
100
> count
101
mongosniff output:
127.0.0.1:54977 -->> 127.0.0.1:27017 ruby-test-db.test 51 bytes id:a 10
query: {} ntoreturn: 100 ntoskip: 0
127.0.0.1:27017 <<-- 127.0.0.1:54977 ?e?*?|y 13869 bytes id:2667 9831 - 10
reply n:100 cursorId: 8754037985523367853
{ _id: ObjectId('4fce22c3977225f8cb3b5ad1'), A1338909379446: 1338909379.447, A1338909379447: 1338909379.448, A1338909379448: 1338909379.449, A1338909379449: 1338909379.449, xyz: 1, abc: 330 }
127.0.0.1:54977 -->> 127.0.0.1:27017 ruby-test-db.test 50 bytes id:b 11
getMore nToReturn: 100 cursorId: 8754037985523367853
127.0.0.1:27017 <<-- 127.0.0.1:54977 227 bytes id:2668 9832 - 11
reply n:1 cursorId: 0
{ _id: ObjectId('4fce22c3977225f8cb3b5aea'), A1338909379578: 1338909379.584, A1338909379584: 1338909379.585, A1338909379585: 1338909379.588, A1338909379588: 1338909379.589, A1338909379589: 1338909379.59, A133890937959: 1338909379.59, xyz: 1, abc: 30 }
Now, when I supply a sort criteria to the query, the batchsize acts as a limit and immediately closes the cursor on the server.
> var cursor = db.test.find().sort({ abc: 1 }).batchSize(100);
> var count = 0;
> while(cursor.hasNext()) { cursor.next(); count++; }
99
> count
100
mongosniff output:
query: { query: {}, orderby: { abc: 1.0 } } ntoreturn: 100 ntoskip: 0
127.0.0.1:27017 <<-- 127.0.0.1:54977 13916 bytes id:2678 9848 - 27
reply n:100 cursorId: 0
{ _id: ObjectId('4fce22c3977225f8cb3b5acf'), A1338909379437: 1338909379.438, A1338909379438: 1338909379.439, A1338909379439: 1338909379.44, A133890937944: 1338909379.44, xyz: 1, abc: 2 }
In this scenario, any further results past the end of the first returned batch are effectively ignored. Not good if you need them!
- duplicates
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SERVER-5374 batchSize is a hard limit for an in memory sort
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- Closed
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- related to
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- Closed
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