How does a Pageable request works? - mongodb

Question

I have a Pageable request which query for about 1.6 millions documents and each request limit the response to 1000 documents. The query use an index... Well at least it should... I'm using db.currentOp() to look for the request that takes a while to process. When I launched the query (yesterday at 01:00PM) it used the index for each portion of 1000. But it seems that at some point he decided not to use it anymore... And I can't figure out why...
I also have a command operation for the same query and it is using the index.
{
"desc" : "conn7758",
"threadId" : "1012",
"connectionId" : 7758,
"client" : "10.10.10.3:64670",
"clientMetadata" : {
"driver" : {
"name" : "mongo-java-driver",
"version" : "unknown"
},
"os" : {
"type" : "Windows",
"name" : "Windows Server 2008 R2",
"architecture" : "x86",
"version" : "6.1"
},
"platform" : "Java/Oracle Corporation/1.8.0_73-b02"
},
"active" : true,
"opid" : 119588895,
"secs_running" : 1299,
"microsecs_running" : NumberLong(1299666014),
"op" : "command",
"ns" : "thingsplay.data",
"query" : {
"count" : "data",
"query" : {
"device" : "S000110",
"topic" : "INPUTS/COIL1000",
"date" : {
"$gt" : ISODate("2015-08-08T06:00:00Z"),
"$lt" : ISODate("2018-06-14T11:28:08.369Z")
}
}
},
"planSummary" : "IXSCAN { device: 1, topic: 1, vhost: 1}",
"numYields" : 81449,
"locks" : {
"Global" : "r",
"Database" : "r",
"Collection" : "r"
},
"waitingForLock" : false,
"lockStats" : {
"Global" : {
"acquireCount" : {
"r" : NumberLong(162900)
}
},
"Database" : {
"acquireCount" : {
"r" : NumberLong(81450)
}
},
"Collection" : {
"acquireCount" : {
"r" : NumberLong(81450)
}
}
}
}
The request is still running... and I think it will be for a couple of hours.
Here is the last operations that is running :
{
"desc" : "conn7758",
"threadId" : "1012",
"connectionId" : 7758,
"client" : "10.10.10.3:64670",
"clientMetadata" : {
"driver" : {
"name" : "mongo-java-driver",
"version" : "unknown"
},
"os" : {
"type" : "Windows",
"name" : "Windows Server 2008 R2",
"architecture" : "x86",
"version" : "6.1"
},
"platform" : "Java/Oracle Corporation/1.8.0_73-b02"
},
"active" : true,
"opid" : 120813021,
"secs_running" : 134,
"microsecs_running" : NumberLong(134586683),
"op" : "query",
"ns" : "thingsplay.data",
"query" : {
"find" : "data",
"filter" : {
"device" : "S000110",
"topic" : "INPUTS/COIL1000",
"date" : {
"$gt" : ISODate("2015-08-08T06:00:00Z"),
"$lt" : ISODate("2018-06-14T11:28:08.369Z")
}
},
"projection" : {
},
"skip" : 1124000,
"limit" : 1000
},
"numYields" : 8445,
"locks" : {
"Global" : "r",
"Database" : "r",
"Collection" : "r"
},
"waitingForLock" : false,
"lockStats" : {
"Global" : {
"acquireCount" : {
"r" : NumberLong(16892)
}
},
"Database" : {
"acquireCount" : {
"r" : NumberLong(8446)
}
},
"Collection" : {
"acquireCount" : {
"r" : NumberLong(8446)
}
}
}
}
Unfortunately I don't have the operation of the first operations that went well but you can see here that it doesn't use the index.
[
{
"v" : 2,
"key" : {
"_id" : 1
},
"name" : "_id_",
"ns" : "thingsplay.data"
},
{
"v" : 2,
"key" : {
"device" : 1,
"topic" : 1,
"date" : 1
},
"name" : "device_1_topic_1_date_1",
"ns" : "thingsplay.data",
"background" : true
},
{
"v" : 2,
"key" : {
"device" : 1,
"topic" : 1,
"vhost" : 1
},
"name" : "device_1_topic_1_vhost_1",
"ns" : "thingsplay.data",
"background" : true
}
]