如题
这是我用explain显示出来的数据
> db.users.explain("allPlansExecution").find({username:'user101'}) { "queryPlanner" : { "plannerVersion" : 1, "namespace" : "test.users", "indexFilterSet" : false, "parsedQuery" : { "username" : { "$eq" : "user101" } }, "winningPlan" : { "stage" : "FETCH", "inputStage" : { "stage" : "IXSCAN", "keyPattern" : { "username" : 1 }, "indexName" : "username_1", "isMultiKey" : false, "direction" : "forward", "indexBounds" : { "username" : [ "[\"user101\", \"user101\"]" ] } } }, "rejectedPlans" : [ ] }, "executionStats" : { "executionSuccess" : true, "nReturned" : 1, "executionTimeMillis" : 0, "totalKeysExamined" : 1, "totalDocsExamined" : 1, "executionStages" : { "stage" : "FETCH", "nReturned" : 1, "executionTimeMillisEstimate" : 0, "works" : 2, "advanced" : 1, "needTime" : 0, "needFetch" : 0, "saveState" : 0, "restoreState" : 0, "isEOF" : 1, "invalidates" : 0, "docsExamined" : 1, "alreadyHasObj" : 0, "inputStage" : { "stage" : "IXSCAN", "nReturned" : 1, "executionTimeMillisEstimate" : 0, "works" : 2, "advanced" : 1, "needTime" : 0, "needFetch" : 0, "saveState" : 0, "restoreState" : 0, "isEOF" : 1, "invalidates" : 0, "keyPattern" : { "username" : 1 }, "indexName" : "username_1", "isMultiKey" : false, "direction" : "forward", "indexBounds" : { "username" : [ "[\"user101\", \"user101\"]" ] }, "keysExamined" : 1, "dupsTested" : 0, "dupsDropped" : 0, "seenInvalidated" : 0, "matchTested" : 0 } }, "allPlansExecution" : [ ] }, "serverInfo" : { "host" : "mongo2", "port" : 27017, "version" : "3.0.0", "gitVersion" : "a841fd6394365954886924a35076691b4d149168" }, "ok" : 1 }
I just checked the documentation, and I blame myself for not looking at the results carefully. .
queryPlanner.winningPlan.inputStage.stage
Column display query strategy-
IXSCAN
means using Index query-
COLLSCAN
means using column query, that is, comparing the past one by one
Used incursor
中的索引名称移动到了queryPlanner.winningPlan.inputStage.indexName
3.0
executionStats.totalDocsExamined
来显示总共需要检查的文档数,用以取而代之nscanned
.