Mongo 3.2子文件索引问题

Question

最近我们将MongoDB 2.6（MMAPV1）升级到3.2（MMAPV1），子文档中的升级索引无效。我用查询解释在两个数据库上做了一个小概念验证。

在MongoDB 3.2中，不考虑子文档索引，有人可以建议修复此问题吗？

这是示例mongo文档，

{
    "_id" : ObjectId("58bff13e4e6904293cc206b4"),
    "Value" : NumberLong(158),
    "OVGuid" : NumberLong(0),
    "Name" : "User 08/03/2017 03.55.42.782",
    "CreateDate" : ISODate("2017-03-08T11:55:42.783Z"),
    "RoleLst" : [ 
        {
            "_id" : NumberLong(146),
            "Name" : "Role1"
        }, 
        {
            "_id" : NumberLong(108),
            "Name" : "Role2"
        }, 
        {
            "_id" : NumberLong(29),
            "Name" : "Role3"
        }
    ]
}

在Mongo DB 2.6中，我在＆＃34; RoleLst._id＆＃34;（db.User.createIndex（{＆＃34; RoleLst._id＆＃34;：1}））中插入了近100,000个数据并启用了索引和3.2。

然后我尝试了查询解释

db.User.find（{＆＃34; RoleLst＆＃34;：{＆＃34; $ elemMatch＆＃34;：{＆＃34; _id＆＃34;：NumberLong（200）}}}）。解释（）

这是我从3.2得到的结果

Explain for sub-document query

{
    "queryPlanner" : {
        "plannerVersion" : 1,
        "namespace" : "SubDocmentIndexChecking.User",
        "indexFilterSet" : false,
        "parsedQuery" : {
            "RoleLst" : {
                "$elemMatch" : {
                    "_id" : {
                        "$eq" : NumberLong(200)
                    }
                }
            }
        },
        "winningPlan" : {
            "stage" : "COLLSCAN",
            "filter" : {
                "RoleLst" : {
                    "$elemMatch" : {
                        "_id" : {
                            "$eq" : NumberLong(200)
                        }
                    }
                }
            },
            "direction" : "forward"
        },
        "rejectedPlans" : []
    },
    "serverInfo" : {
        "host" : "******",
        "port" : ******,
        "version" : "3.2.10",
        "gitVersion" : "79d9b3ab5ce20f51c272b4411202710a082d0317"
    },
    "ok" : 1.0
}

这是我从2.6

获得的结果

Explain for sub-document query 
    {
        "cursor" : "BtreeCursor RoleLst._id_1",
        "isMultiKey" : true,
        "n" : 0,
        "nscannedObjects" : 0,
        "nscanned" : 0,
        "nscannedObjectsAllPlans" : 0,
        "nscannedAllPlans" : 0,
        "scanAndOrder" : false,
        "indexOnly" : false,
        "nYields" : 0,
        "nChunkSkips" : 0,
        "millis" : 0,
        "indexBounds" : {
            "RoleLst._id" : [ 
                [ 
                    NumberLong(200), 
                    NumberLong(200)
                ]
            ]
        },
        "server" : "***********",
        "filterSet" : false,
        "stats" : {
            "type" : "KEEP_MUTATIONS",
            "works" : 2,
            "yields" : 0,
            "unyields" : 0,
            "invalidates" : 0,
            "advanced" : 0,
            "needTime" : 1,
            "needFetch" : 0,
            "isEOF" : 1,
            "children" : [ 
                {
                    "type" : "FETCH",
                    "works" : 2,
                    "yields" : 0,
                    "unyields" : 0,
                    "invalidates" : 0,
                    "advanced" : 0,
                    "needTime" : 1,
                    "needFetch" : 0,
                    "isEOF" : 1,
                    "alreadyHasObj" : 0,
                    "forcedFetches" : 0,
                    "matchTested" : 0,
                    "children" : [ 
                        {
                            "type" : "IXSCAN",
                            "works" : 1,
                            "yields" : 0,
                            "unyields" : 0,
                            "invalidates" : 0,
                            "advanced" : 0,
                            "needTime" : 1,
                            "needFetch" : 0,
                            "isEOF" : 1,
                            "keyPattern" : "{ RoleLst._id: 1.0 }",
                            "isMultiKey" : 1,
                            "boundsVerbose" : "field #0['RoleLst._id']: [200, 200]",
                            "yieldMovedCursor" : 0,
                            "dupsTested" : 0,
                            "dupsDropped" : 0,
                            "seenInvalidated" : 0,
                            "matchTested" : 0,
                            "keysExamined" : 0,
                            "children" : []
                        }
                    ]
                }
            ]
        }
    }