此查询需要66秒：
{
"op" : "query",
"ns" : "pipelines_odd.CachedUrl_319",
"query" : {
"find" : "CachedUrl_319",
"filter" : {
"$and" : [
{
"updated_at" : {
"$lt" : ISODate("2016-03-23T19:26:36.207Z")
}
},
{
"host_pattern_id" : 1844
}
]
},
"ntoreturn" : 100,
"sort" : {
"updated_at" : 1
}
},
"keysExamined" : 0,
"docsExamined" : 0,
"hasSortStage" : true,
"cursorExhausted" : true,
"keyUpdates" : 0,
"writeConflicts" : 0,
"numYield" : 18150,
"locks" : {
"Global" : {
"acquireCount" : {
"r" : NumberLong(36302)
},
"acquireWaitCount" : {
"r" : NumberLong(3078)
},
"timeAcquiringMicros" : {
"r" : NumberLong(3054408)
}
},
"Database" : {
"acquireCount" : {
"r" : NumberLong(18151)
}
},
"Collection" : {
"acquireCount" : {
"r" : NumberLong(18151)
}
}
},
"nreturned" : 0,
"responseLength" : 20,
"millis" : 66576,
"execStats" : {
"stage" : "ENSURE_SORTED",
"nReturned" : 0,
"executionTimeMillisEstimate" : 0,
"works" : 6,
"advanced" : 0,
"needTime" : 5,
"needYield" : 0,
"saveState" : 0,
"restoreState" : 0,
"isEOF" : 1,
"invalidates" : 0,
"nDropped" : 0,
"inputStage" : {
"stage" : "OR",
"nReturned" : 0,
"executionTimeMillisEstimate" : 0,
"works" : 6,
"advanced" : 0,
"needTime" : 5,
"needYield" : 0,
"saveState" : 0,
"restoreState" : 0,
"isEOF" : 1,
"invalidates" : 0,
"dupsTested" : 0,
"dupsDropped" : 0,
"locsForgotten" : 0,
"inputStages" : [
{
"stage" : "SORT",
"nReturned" : 0,
"executionTimeMillisEstimate" : 0,
"works" : 3,
"advanced" : 0,
"needTime" : 2,
"needYield" : 0,
"saveState" : 0,
"restoreState" : 0,
"isEOF" : 1,
"invalidates" : 0,
"sortPattern" : {
"updated_at" : 1
},
"memUsage" : 0,
"memLimit" : 33554432,
"limitAmount" : 100,
"inputStage" : {
"stage" : "SORT_KEY_GENERATOR",
"nReturned" : 0,
"executionTimeMillisEstimate" : 0,
"works" : 2,
"advanced" : 0,
"needTime" : 1,
"needYield" : 0,
"saveState" : 0,
"restoreState" : 0,
"isEOF" : 1,
"invalidates" : 0,
"inputStage" : {
"stage" : "FETCH",
"filter" : {
"updated_at" : {
"$lt" : ISODate("2016-03-23T19:26:36.207Z")
}
},
"nReturned" : 0,
"executionTimeMillisEstimate" : 0,
"works" : 1,
"advanced" : 0,
"needTime" : 0,
"needYield" : 0,
"saveState" : 0,
"restoreState" : 0,
"isEOF" : 1,
"invalidates" : 0,
"docsExamined" : 0,
"alreadyHasObj" : 0,
"inputStage" : {
"stage" : "IXSCAN",
"nReturned" : 0,
"executionTimeMillisEstimate" : 0,
"works" : 1,
"advanced" : 0,
"needTime" : 0,
"needYield" : 0,
"saveState" : 0,
"restoreState" : 0,
"isEOF" : 1,
"invalidates" : 0,
"keyPattern" : {
"host_pattern_id" : 1
},
"indexName" : "host_pattern_id_1",
"isMultiKey" : false,
"isUnique" : false,
"isSparse" : false,
"isPartial" : false,
"indexVersion" : 1,
"direction" : "forward",
"indexBounds" : {
"host_pattern_id" : [
"[1844, 1844]"
]
},
"keysExamined" : 0,
"dupsTested" : 0,
"dupsDropped" : 0,
"seenInvalidated" : 0
}
}
}
},
{
"stage" : "SORT",
"nReturned" : 0,
"executionTimeMillisEstimate" : 0,
"works" : 3,
"advanced" : 0,
"needTime" : 2,
"needYield" : 0,
"saveState" : 0,
"restoreState" : 0,
"isEOF" : 1,
"invalidates" : 0,
"sortPattern" : {
"updated_at" : 1
},
"memUsage" : 0,
"memLimit" : 33554432,
"inputStage" : {
"stage" : "SORT_KEY_GENERATOR",
"nReturned" : 0,
"executionTimeMillisEstimate" : 0,
"works" : 2,
"advanced" : 0,
"needTime" : 1,
"needYield" : 0,
"saveState" : 0,
"restoreState" : 0,
"isEOF" : 1,
"invalidates" : 0,
"inputStage" : {
"stage" : "FETCH",
"filter" : {
"updated_at" : {
"$lt" : ISODate("2016-03-23T19:26:36.207Z")
}
},
"nReturned" : 0,
"executionTimeMillisEstimate" : 0,
"works" : 1,
"advanced" : 0,
"needTime" : 0,
"needYield" : 0,
"saveState" : 0,
"restoreState" : 0,
"isEOF" : 1,
"invalidates" : 0,
"docsExamined" : 0,
"alreadyHasObj" : 0,
"inputStage" : {
"stage" : "IXSCAN",
"nReturned" : 0,
"executionTimeMillisEstimate" : 0,
"works" : 1,
"advanced" : 0,
"needTime" : 0,
"needYield" : 0,
"saveState" : 0,
"restoreState" : 0,
"isEOF" : 1,
"invalidates" : 0,
"keyPattern" : {
"host_pattern_id" : 1
},
"indexName" : "host_pattern_id_1",
"isMultiKey" : false,
"isUnique" : false,
"isSparse" : false,
"isPartial" : false,
"indexVersion" : 1,
"direction" : "forward",
"indexBounds" : {
"host_pattern_id" : [
"[1844, 1844]"
]
},
"keysExamined" : 0,
"dupsTested" : 0,
"dupsDropped" : 0,
"seenInvalidated" : 0
}
}
}
}
]
}
},
"ts" : ISODate("2016-03-30T19:27:56.347Z"),
"allUsers" : [ ],
"user" : ""
}
虽然针对大小相同的不同集合的类似查询在10毫秒内运行：
{
"op" : "query",
"ns" : "pipelines_odd.CachedUrl_257",
"query" : {
"find" : "CachedUrl_257",
"filter" : {
"$or" : [
{
"$and" : [
{
"updated_at" : {
"$lt" : ISODate("2016-01-23T20:55:52.174Z")
}
},
{
"host_pattern_id" : 5046
}
]
}
]
},
"ntoreturn" : 100,
"sort" : {
"updated_at" : 1
}
},
"cursorid" : NumberLong("16448827549027"),
"keysExamined" : 100,
"docsExamined" : 100,
"keyUpdates" : 0,
"writeConflicts" : 0,
"numYield" : 1,
"locks" : {
"Global" : {
"acquireCount" : {
"r" : NumberLong(4)
}
},
"Database" : {
"acquireCount" : {
"r" : NumberLong(2)
}
},
"Collection" : {
"acquireCount" : {
"r" : NumberLong(2)
}
}
},
"nreturned" : 100,
"responseLength" : 42183,
"millis" : 10,
"execStats" : {
"stage" : "CACHED_PLAN",
"nReturned" : 100,
"executionTimeMillisEstimate" : 10,
"works" : 100,
"advanced" : 100,
"needTime" : 0,
"needYield" : 0,
"saveState" : 2,
"restoreState" : 1,
"isEOF" : 0,
"invalidates" : 0,
"inputStage" : {
"stage" : "FETCH",
"filter" : {
"host_pattern_id" : {
"$eq" : 5046
}
},
"nReturned" : 100,
"executionTimeMillisEstimate" : 10,
"works" : 100,
"advanced" : 100,
"needTime" : 0,
"needYield" : 0,
"saveState" : 2,
"restoreState" : 1,
"isEOF" : 0,
"invalidates" : 0,
"docsExamined" : 100,
"alreadyHasObj" : 0,
"inputStage" : {
"stage" : "IXSCAN",
"nReturned" : 100,
"executionTimeMillisEstimate" : 0,
"works" : 100,
"advanced" : 100,
"needTime" : 0,
"needYield" : 0,
"saveState" : 2,
"restoreState" : 1,
"isEOF" : 0,
"invalidates" : 0,
"keyPattern" : {
"updated_at" : 1
},
"indexName" : "updated_at_1",
"isMultiKey" : false,
"isUnique" : false,
"isSparse" : false,
"isPartial" : false,
"indexVersion" : 1,
"direction" : "forward",
"indexBounds" : {
"updated_at" : [
"(true, new Date(1453582552174))"
]
},
"keysExamined" : 100,
"dupsTested" : 0,
"dupsDropped" : 0,
"seenInvalidated" : 0
}
}
},
"ts" : ISODate("2016-03-23T20:55:40.203Z"),
"allUsers" : [ ],
"user" : ""
}
两个集合都有相似的大小和相同的索引：
PipelinesCluster1:SECONDARY> db.CachedUrl_319.count()
24383730
PipelinesCluster1:SECONDARY> db.CachedUrl_319.getIndexes()
[
{
"ns" : "pipelines_odd.CachedUrl_319",
"v" : 1,
"key" : {
"_id" : 1
},
"name" : "_id_"
},
{
"ns" : "pipelines_odd.CachedUrl_319",
"v" : 1,
"key" : {
"updated_at" : 1
},
"name" : "updated_at_1",
"background" : true
},
{
"ns" : "pipelines_odd.CachedUrl_319",
"v" : 1,
"key" : {
"host_pattern_id" : 1
},
"name" : "host_pattern_id_1",
"background" : true
}
]
PipelinesCluster1:SECONDARY> db.CachedUrl_257.count()
24697281
PipelinesCluster1:SECONDARY> db.CachedUrl_257.getIndexes()
[
{
"ns" : "pipelines_odd.CachedUrl_257",
"v" : 1,
"key" : {
"_id" : 1
},
"name" : "_id_"
},
{
"ns" : "pipelines_odd.CachedUrl_257",
"v" : 1,
"key" : {
"updated_at" : 1
},
"name" : "updated_at_1",
"background" : true
},
{
"ns" : "pipelines_odd.CachedUrl_257",
"v" : 1,
"key" : {
"host_pattern_id" : 1
},
"name" : "host_pattern_id_1",
"background" : true
}
]
我了解查询性能可能因数据库负载和其他因素而异，但针对CachedUrl_319的查询始终较慢，而针对CachedUrl_257的查询始终会立即返回。可能导致这种情况的原因有什么办法可以解决它吗？
答案 0 :(得分：0)
我认为你是第二次查询缓存的。
您创建了一个索引，因此mongodb会自动为您处理缓存。 常见问题@ mongodb.org
如果你看一下你在execStats
中发布的第二个system.profile集合 "execStats" : {
"stage" : "CACHED_PLAN", <-- you were cached
将它与第一个进行比较，您将看到第一个system.profile集合具有不同的阶段，例如
"execStats" : {
"stage" : "ENSURE_SORTED"
您还可以查看＆＃34; inputStage＆＃34; ，你会看到第二个刚刚取出。
"inputStage" : {
"stage" : "FETCH",
第一个做得更多，例如＆＃34; SORT＆＃34;和＆＃34; SORT_KEY_GENERATOR＆＃34;。