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Type:
Task
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Resolution: Won't Do
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Priority:
Major - P3
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Affects Version/s: None
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Labels:None
1. module info:
db version v3.2.4
git version: nogitversion
allocator: tcmalloc
modules: none
build environment:
distarch: x86_64
target_arch: x86_64
2. issue info
The following is the OP_REPLY struct of mongodb wire protocol.
_struct {
MsgHeader header; // standard message header
int32 responseFlags; // bit vector - see details below
int64 cursorID; // cursor id if client needs to do get more's
int32 startingFrom; // where in the cursor this reply is starting
int32 numberReturned; // number of documents in the reply
document* documents; // documents
}_
When the cursorID is set to non-zero in a reply, it implies there are more data, and client should do get more's.
However, the cursorID is always set to zero in replies of aggregate request, even if there are more data. Actually the cursor id is set in the "documents"..
This behavior is not following the standard protocol.
3. request&reply info
the request is like that:
??
[
{
"$match" : {
"_isdelete" : 0,
"_uid" : 444629226
}
},
{
"$group" : {
"ctime" : {
"$max" : "$ctime"
},
"_id" : {
"name" : "$name"
}
}
},
{
"$sort" : {
"_id" : 1
}
},
{
"$skip" : 0
},
{
"$limit" : 400
}
]
??
the reply bytes is like that:
messageLength: 40263
requestID:125067217
responseTo:9
opCode: OP_REPLY
responseFlags:0x4
cursorID:0
startingFrom:0
numberReturned: 1
documents: {
"waitedMS":0,
"cursor": {
"id":22321923528,
"ns": "test.test0"
"firstBatch": ...
}