we have a three nodes Mongo 3.6.11 cluster with a PSA replica set. we start syncing a newly attached node, syncing starts fast but after a while turned very slowly. during syncing this query is unexpectedly slow:
db.Cartable_Task.find(
{ $and: [ { "oprator": { $in: [ "fec48cfa-998c-4c53-b0a6-8a194e3d37ab" ] } } ], "deleted": false }
).sort( { "content.officialDate": -1, "_id": -1 }).skip(150).limit(10)
and result of explain("executionStats") is :
{
"queryPlanner" : {
"plannerVersion" : 1,
"namespace" : "kateb.Cartable_Task",
"indexFilterSet" : false,
"parsedQuery" : {
"$and" : [
{
"deleted" : {
"$eq" : false
}
},
{
"oprator" : {
"$eq" : "fec48cfa-998c-4c53-b0a6-8a194e3d37ab"
}
}
]
},
"winningPlan" : {
"stage" : "LIMIT",
"limitAmount" : 10,
"inputStage" : {
"stage" : "FETCH",
"inputStage" : {
"stage" : "SKIP",
"skipAmount" : 0,
"inputStage" : {
"stage" : "IXSCAN",
"keyPattern" : {
"deleted" : 1,
"oprator" : 1,
"content.officialDate" : -1,
"_id" : -1
},
"indexName" : "deleted_1_oprator_1_content.officialDate_-1__id_-1",
"isMultiKey" : false,
"multiKeyPaths" : {
"deleted" : [ ],
"oprator" : [ ],
"content.officialDate" : [ ],
"_id" : [ ]
},
"isUnique" : false,
"isSparse" : false,
"isPartial" : false,
"indexVersion" : 2,
"direction" : "forward",
"indexBounds" : {
"deleted" : [
"[false, false]"
],
"oprator" : [
"[\"fec48cfa-998c-4c53-b0a6-8a194e3d37ab\", \"fec48cfa-998c-4c53-b0a6-8a194e3d37ab\"]"
],
"content.officialDate" : [
"[MaxKey, MinKey]"
],
"_id" : [
"[MaxKey, MinKey]"
]
}
}
}
}
},
"rejectedPlans" : [ *** ]
},
"executionStats" : {
"executionSuccess" : true,
"nReturned" : 10,
"executionTimeMillis" : 115425,
"totalKeysExamined" : 160,
"totalDocsExamined" : 10,
"executionStages" : {
"stage" : "LIMIT",
"nReturned" : 10,
"executionTimeMillisEstimate" : 4862,
"works" : 161,
"advanced" : 10,
"needTime" : 150,
"needYield" : 0,
"saveState" : 221,
"restoreState" : 221,
"isEOF" : 1,
"invalidates" : 0,
"limitAmount" : 10,
"inputStage" : {
"stage" : "FETCH",
"nReturned" : 10,
"executionTimeMillisEstimate" : 4862,
"works" : 160,
"advanced" : 10,
"needTime" : 150,
"needYield" : 0,
"saveState" : 221,
"restoreState" : 221,
"isEOF" : 0,
"invalidates" : 0,
"docsExamined" : 10,
"alreadyHasObj" : 0,
"inputStage" : {
"stage" : "SKIP",
"nReturned" : 10,
"executionTimeMillisEstimate" : 280,
"works" : 160,
"advanced" : 10,
"needTime" : 150,
"needYield" : 0,
"saveState" : 221,
"restoreState" : 221,
"isEOF" : 0,
"invalidates" : 0,
"skipAmount" : 0,
"inputStage" : {
"stage" : "IXSCAN",
"nReturned" : 160,
"executionTimeMillisEstimate" : 280,
"works" : 160,
"advanced" : 160,
"needTime" : 0,
"needYield" : 0,
"saveState" : 221,
"restoreState" : 221,
"isEOF" : 0,
"invalidates" : 0,
"keyPattern" : {
"deleted" : 1,
"oprator" : 1,
"content.officialDate" : -1,
"_id" : -1
},
"indexName" : "deleted_1_oprator_1_content.officialDate_-1__id_-1",
"isMultiKey" : false,
"multiKeyPaths" : {
"deleted" : [ ],
"oprator" : [ ],
"content.officialDate" : [ ],
"_id" : [ ]
},
"isUnique" : false,
"isSparse" : false,
"isPartial" : false,
"indexVersion" : 2,
"direction" : "forward",
"indexBounds" : {
"deleted" : [
"[false, false]"
],
"oprator" : [
"[\"fec48cfa-998c-4c53-b0a6-8a194e3d37ab\", \"fec48cfa-998c-4c53-b0a6-8a194e3d37ab\"]"
],
"content.officialDate" : [
"[MaxKey, MinKey]"
],
"_id" : [
"[MaxKey, MinKey]"
]
},
"keysExamined" : 160,
"seeks" : 1,
"dupsTested" : 0,
"dupsDropped" : 0,
"seenInvalidated" : 0
}
}
}
}
},
"serverInfo" : {
"host" : "KMongoDb3",
"port" : 27017,
"version" : "3.6.11",
"gitVersion" : "b4339db12bf57ffee5b84a95c6919dbd35fe31c9"
},
"ok" : 1,
"operationTime" : Timestamp(1684344748, 1),
"$clusterTime" : {
"clusterTime" : Timestamp(1684344748, 1),
"signature" : {
"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
"keyId" : NumberLong(0)
}
}
}
I checked CPU, Memory and disk IO usage, and none are full.