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Type:
Question
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Resolution: Done
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Priority:
Major - P3
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Affects Version/s: 3.0.2
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Component/s: Querying, WiredTiger
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Hello,
I have a compound index on a collection:
{
"v" : 1,
"key" : {
"sdk.id" : 1,
"sdk.createdAt" : 1,
"sdk.updatedAt" : 1,
"deviceInfo.isTablet" : 1
},
"name" : "sdk.id_1_sdk.createdAt_1_sdk.updatedAt_1_deviceInfo.isTablet_1",
"ns" : "company.Device"
}
The documents contains an array of subdocument, stored in 'sdk' property.
When I try to query the collection on the sdk.id field, I have the following result:
db.Device.explain(1).find({'sdk.id': 'id1'});
{
"queryPlanner" : {
"plannerVersion" : 1,
"namespace" : "company.Device",
"indexFilterSet" : false,
"parsedQuery" : {
"sdk.id" : {
"$eq" : "id1"
}
},
"winningPlan" : {
"stage" : "PROJECTION",
"transformBy" : {
"sdk.id" : 1
},
"inputStage" : {
"stage" : "FETCH",
"inputStage" : {
"stage" : "IXSCAN",
"keyPattern" : {
"sdk.id" : 1,
"sdk.createdAt" : 1,
"sdk.updatedAt" : 1,
"deviceInfo.isTablet" : 1
},
"indexName" : "sdk.id_1_sdk.createdAt_1_sdk.updatedAt_1_deviceInfo.isTablet_1",
"isMultiKey" : true,
"direction" : "forward",
"indexBounds" : {
"sdk.id" : [
"[\"id1\", \"id1\"]"
],
"sdk.createdAt" : [
"[MinKey, MaxKey]"
],
"sdk.updatedAt" : [
"[MinKey, MaxKey]"
],
"deviceInfo.isTablet" : [
"[MinKey, MaxKey]"
]
}
}
}
},
"rejectedPlans" : [ ]
},
"executionStats" : {
"executionSuccess" : true,
"nReturned" : 569733,
"executionTimeMillis" : 3435,
"totalKeysExamined" : 569733,
"totalDocsExamined" : 569733,
"executionStages" : {
"stage" : "PROJECTION",
"nReturned" : 569733,
"executionTimeMillisEstimate" : 3331,
"works" : 569734,
"advanced" : 569733,
"needTime" : 0,
"needFetch" : 0,
"saveState" : 4452,
"restoreState" : 4452,
"isEOF" : 1,
"invalidates" : 0,
"transformBy" : {
"sdk.id" : 1
},
"inputStage" : {
"stage" : "FETCH",
"nReturned" : 569733,
"executionTimeMillisEstimate" : 2231,
"works" : 569734,
"advanced" : 569733,
"needTime" : 0,
"needFetch" : 0,
"saveState" : 4452,
"restoreState" : 4452,
"isEOF" : 1,
"invalidates" : 0,
"docsExamined" : 569733,
"alreadyHasObj" : 0,
"inputStage" : {
"stage" : "IXSCAN",
"nReturned" : 569733,
"executionTimeMillisEstimate" : 940,
"works" : 569733,
"advanced" : 569733,
"needTime" : 0,
"needFetch" : 0,
"saveState" : 4452,
"restoreState" : 4452,
"isEOF" : 1,
"invalidates" : 0,
"keyPattern" : {
"sdk.id" : 1,
"sdk.createdAt" : 1,
"sdk.updatedAt" : 1,
"deviceInfo.isTablet" : 1
},
"indexName" : "sdk.id_1_sdk.createdAt_1_sdk.updatedAt_1_deviceInfo.isTablet_1",
"isMultiKey" : true,
"direction" : "forward",
"indexBounds" : {
"sdk.id" : [
"[\"id1\", \"id1\"]"
],
"sdk.createdAt" : [
"[MinKey, MaxKey]"
],
"sdk.updatedAt" : [
"[MinKey, MaxKey]"
],
"deviceInfo.isTablet" : [
"[MinKey, MaxKey]"
]
},
"keysExamined" : 569733,
"dupsTested" : 569733,
"dupsDropped" : 0,
"seenInvalidated" : 0,
"matchTested" : 0
}
}
},
"allPlansExecution" : [ ]
},
"serverInfo" : {
"host" : "replicaset-primary",
"port" : 27000,
"version" : "3.0.2",
"gitVersion" : "6201872043ecbbc0a4cc169b5482dcf385fc464f"
},
"ok" : 1
}
I can't find any info on isEOF and other values such as saveState etc. to debug it. We are using WiredTiger and replica set was setted up on AWS using MMS.
The same query was very fast before the WiredTiger switch
Can someone give us some insight on the explain above ?
Regards,
Jonathan