0

我有一个查询：

{"$query"=>{"user_id"=>"512f7960534dcda22b000491", "$or"=>[{"when_tz"=>{"$gte"=>2010-06-24 04:00:00 UTC, "$lt"=>2010-06-25 04:00:00 UTC}}, {"when_tz"=>{"$gte"=>2011-06-24 04:00:00 UTC, "$lt"=>2011-06-25 04:00:00 UTC}}, {"when_tz"=>{"$gte"=>2012-06-24 04:00:00 UTC, "$lt"=>2012-06-25 04:00:00 UTC}}], "_type"=>{"$in"=>["FacebookImageItem", "FoursquareImageItem", "InstagramItem", "TwitterImageItem", "Image"]}}, "$explain"=>true, "$orderby"=>{"when_tz"=>1}}

和一个索引：

{ user_id: 1, _type: 1, when_tz: 1 }

解释：

{
"cursor": "BtreeCursor user_id_1__type_1_facebook_id_1 multi",
"isMultiKey": false,
"n": 28,
"nscannedObjects": 15094,
"nscanned": 15098,
"nscannedObjectsAllPlans": 181246,
"nscannedAllPlans": 241553,
"scanAndOrder": true,
"indexOnly": false,
"nYields": 12,
"nChunkSkips": 0,
"millis": 2869,
"indexBounds": {
    "user_id": [
        [
            "512f7960534dcda22b000491",
            "512f7960534dcda22b000491"
        ]
    ],
    "_type": [
        [
            "FacebookImageItem",
            "FacebookImageItem"
        ],
        [
            "FoursquareImageItem",
            "FoursquareImageItem"
        ],
        [
            "Image",
            "Image"
        ],
        [
            "InstagramItem",
            "InstagramItem"
        ],
        [
            "TwitterImageItem",
            "TwitterImageItem"
        ]
    ],
    "facebook_id": [
        [
            {
                "$minElement": 1
            },
            {
                "$maxElement": 1
            }
        ]
    ]
},
"allPlans": [
    {
        "cursor": "BtreeCursor user_id_1__type_1_facebook_id_1 multi",
        "n": 28,
        "nscannedObjects": 15094,
        "nscanned": 15098,
        "indexBounds": {
            "user_id": [
                [
                    "512f7960534dcda22b000491",
                    "512f7960534dcda22b000491"
                ]
            ],
            "_type": [
                [
                    "FacebookImageItem",
                    "FacebookImageItem"
                ],
                [
                    "FoursquareImageItem",
                    "FoursquareImageItem"
                ],
                [
                    "Image",
                    "Image"
                ],
                [
                    "InstagramItem",
                    "InstagramItem"
                ],
                [
                    "TwitterImageItem",
                    "TwitterImageItem"
                ]
            ],
            "facebook_id": [
                [
                    {
                        "$minElement": 1
                    },
                    {
                        "$maxElement": 1
                    }
                ]
            ]
        }
    },
    {
        "cursor": "BtreeCursor user_id_1__type_1_twitter_id_1 multi",
        "n": 28,
        "nscannedObjects": 15094,
        "nscanned": 15097,
        "indexBounds": {
            "user_id": [
                [
                    "512f7960534dcda22b000491",
                    "512f7960534dcda22b000491"
                ]
            ],
            "_type": [
                [
                    "FacebookImageItem",
                    "FacebookImageItem"
                ],
                [
                    "FoursquareImageItem",
                    "FoursquareImageItem"
                ],
                [
                    "Image",
                    "Image"
                ],
                [
                    "InstagramItem",
                    "InstagramItem"
                ],
                [
                    "TwitterImageItem",
                    "TwitterImageItem"
                ]
            ],
            "twitter_id": [
                [
                    {
                        "$minElement": 1
                    },
                    {
                        "$maxElement": 1
                    }
                ]
            ]
        }
    },
    {
        "cursor": "BtreeCursor user_id_1__type_1_instagram_id_1 multi",
        "n": 28,
        "nscannedObjects": 15094,
        "nscanned": 15097,
        "indexBounds": {
            "user_id": [
                [
                    "512f7960534dcda22b000491",
                    "512f7960534dcda22b000491"
                ]
            ],
            "_type": [
                [
                    "FacebookImageItem",
                    "FacebookImageItem"
                ],
                [
                    "FoursquareImageItem",
                    "FoursquareImageItem"
                ],
                [
                    "Image",
                    "Image"
                ],
                [
                    "InstagramItem",
                    "InstagramItem"
                ],
                [
                    "TwitterImageItem",
                    "TwitterImageItem"
                ]
            ],
            "instagram_id": [
                [
                    {
                        "$minElement": 1
                    },
                    {
                        "$maxElement": 1
                    }
                ]
            ]
        }
    },
    {
        "cursor": "BtreeCursor user_id_1__type_1_foursquare_id_1 multi",
        "n": 28,
        "nscannedObjects": 15094,
        "nscanned": 15097,
        "indexBounds": {
            "user_id": [
                [
                    "512f7960534dcda22b000491",
                    "512f7960534dcda22b000491"
                ]
            ],
            "_type": [
                [
                    "FacebookImageItem",
                    "FacebookImageItem"
                ],
                [
                    "FoursquareImageItem",
                    "FoursquareImageItem"
                ],
                [
                    "Image",
                    "Image"
                ],
                [
                    "InstagramItem",
                    "InstagramItem"
                ],
                [
                    "TwitterImageItem",
                    "TwitterImageItem"
                ]
            ],
            "foursquare_id": [
                [
                    {
                        "$minElement": 1
                    },
                    {
                        "$maxElement": 1
                    }
                ]
            ]
        }
    },
    {
        "cursor": "BtreeCursor user_id_1_phash_1",
        "n": 21,
        "nscannedObjects": 15097,
        "nscanned": 15097,
        "indexBounds": {
            "user_id": [
                [
                    "512f7960534dcda22b000491",
                    "512f7960534dcda22b000491"
                ]
            ],
            "phash": [
                [
                    {
                        "$minElement": 1
                    },
                    {
                        "$maxElement": 1
                    }
                ]
            ]
        }
    },
    {
        "cursor": "BtreeCursor user_id_1_aperature_1_shutter_speed_1_when_tz_1",
        "n": 25,
        "nscannedObjects": 35,
        "nscanned": 15097,
        "indexBounds": {
            "user_id": [
                [
                    "512f7960534dcda22b000491",
                    "512f7960534dcda22b000491"
                ]
            ],
            "aperature": [
                [
                    {
                        "$minElement": 1
                    },
                    {
                        "$maxElement": 1
                    }
                ]
            ],
            "shutter_speed": [
                [
                    {
                        "$minElement": 1
                    },
                    {
                        "$maxElement": 1
                    }
                ]
            ],
            "when_tz": [
                [
                    {
                        "$minElement": 1
                    },
                    {
                        "$maxElement": 1
                    }
                ]
            ]
        }
    },
    {
        "cursor": "BtreeCursor user_id_1_image_hash_1",
        "n": 22,
        "nscannedObjects": 15097,
        "nscanned": 15097,
        "indexBounds": {
            "user_id": [
                [
                    "512f7960534dcda22b000491",
                    "512f7960534dcda22b000491"
                ]
            ],
            "image_hash": [
                [
                    {
                        "$minElement": 1
                    },
                    {
                        "$maxElement": 1
                    }
                ]
            ]
        }
    },
    {
        "cursor": "BtreeCursor user_id_1_time_zone_guessed_1_when_tz_-1",
        "n": 23,
        "nscannedObjects": 32,
        "nscanned": 15097,
        "indexBounds": {
            "user_id": [
                [
                    "512f7960534dcda22b000491",
                    "512f7960534dcda22b000491"
                ]
            ],
            "time_zone_guessed": [
                [
                    {
                        "$minElement": 1
                    },
                    {
                        "$maxElement": 1
                    }
                ]
            ],
            "when_tz": [
                [
                    {
                        "$maxElement": 1
                    },
                    {
                        "$minElement": 1
                    }
                ]
            ]
        }
    },
    {
        "cursor": "BtreeCursor user_id_1_time_zone_guessed_1_when_tz_1",
        "n": 24,
        "nscannedObjects": 33,
        "nscanned": 15097,
        "indexBounds": {
            "user_id": [
                [
                    "512f7960534dcda22b000491",
                    "512f7960534dcda22b000491"
                ]
            ],
            "time_zone_guessed": [
                [
                    {
                        "$minElement": 1
                    },
                    {
                        "$maxElement": 1
                    }
                ]
            ],
            "when_tz": [
                [
                    {
                        "$minElement": 1
                    },
                    {
                        "$maxElement": 1
                    }
                ]
            ]
        }
    },
    {
        "cursor": "BtreeCursor user_id_1_time_zone_guessed_1_when_utc_-1",
        "n": 23,
        "nscannedObjects": 15097,
        "nscanned": 15097,
        "indexBounds": {
            "user_id": [
                [
                    "512f7960534dcda22b000491",
                    "512f7960534dcda22b000491"
                ]
            ],
            "time_zone_guessed": [
                [
                    {
                        "$minElement": 1
                    },
                    {
                        "$maxElement": 1
                    }
                ]
            ],
            "when_utc": [
                [
                    {
                        "$maxElement": 1
                    },
                    {
                        "$minElement": 1
                    }
                ]
            ]
        }
    },
    {
        "cursor": "BtreeCursor user_id_1_time_zone_guessed_1_when_utc_1",
        "n": 24,
        "nscannedObjects": 15097,
        "nscanned": 15097,
        "indexBounds": {
            "user_id": [
                [
                    "512f7960534dcda22b000491",
                    "512f7960534dcda22b000491"
                ]
            ],
            "time_zone_guessed": [
                [
                    {
                        "$minElement": 1
                    },
                    {
                        "$maxElement": 1
                    }
                ]
            ],
            "when_utc": [
                [
                    {
                        "$minElement": 1
                    },
                    {
                        "$maxElement": 1
                    }
                ]
            ]
        }
    },
    {
        "cursor": "BtreeCursor user_id_1_original_shared_item_id_1",
        "n": 24,
        "nscannedObjects": 15097,
        "nscanned": 15097,
        "indexBounds": {
            "user_id": [
                [
                    "512f7960534dcda22b000491",
                    "512f7960534dcda22b000491"
                ]
            ],
            "original_shared_item_id": [
                [
                    {
                        "$minElement": 1
                    },
                    {
                        "$maxElement": 1
                    }
                ]
            ]
        }
    },
    {
        "cursor": "BtreeCursor user_id_1__type_1_s3_tmp_file_1 multi",
        "n": 28,
        "nscannedObjects": 15094,
        "nscanned": 15097,
        "indexBounds": {
            "user_id": [
                [
                    "512f7960534dcda22b000491",
                    "512f7960534dcda22b000491"
                ]
            ],
            "_type": [
                [
                    "FacebookImageItem",
                    "FacebookImageItem"
                ],
                [
                    "FoursquareImageItem",
                    "FoursquareImageItem"
                ],
                [
                    "Image",
                    "Image"
                ],
                [
                    "InstagramItem",
                    "InstagramItem"
                ],
                [
                    "TwitterImageItem",
                    "TwitterImageItem"
                ]
            ],
            "s3_tmp_file": [
                [
                    {
                        "$minElement": 1
                    },
                    {
                        "$maxElement": 1
                    }
                ]
            ]
        }
    },
    {
        "cursor": "BtreeCursor user_id_1__type_1_processed_-1_uploaded_-1_image_device_1 multi",
        "n": 28,
        "nscannedObjects": 15094,
        "nscanned": 15097,
        "indexBounds": {
            "user_id": [
                [
                    "512f7960534dcda22b000491",
                    "512f7960534dcda22b000491"
                ]
            ],
            "_type": [
                [
                    "FacebookImageItem",
                    "FacebookImageItem"
                ],
                [
                    "FoursquareImageItem",
                    "FoursquareImageItem"
                ],
                [
                    "Image",
                    "Image"
                ],
                [
                    "InstagramItem",
                    "InstagramItem"
                ],
                [
                    "TwitterImageItem",
                    "TwitterImageItem"
                ]
            ],
            "processed": [
                [
                    {
                        "$maxElement": 1
                    },
                    {
                        "$minElement": 1
                    }
                ]
            ],
            "uploaded": [
                [
                    {
                        "$maxElement": 1
                    },
                    {
                        "$minElement": 1
                    }
                ]
            ],
            "image_device": [
                [
                    {
                        "$minElement": 1
                    },
                    {
                        "$maxElement": 1
                    }
                ]
            ]
        }
    },
    {
        "cursor": "BtreeCursor user_id_1__type_1_when_tz_1 multi",
        "n": 28,
        "nscannedObjects": 28,
        "nscanned": 15097,
        "indexBounds": {
            "user_id": [
                [
                    "512f7960534dcda22b000491",
                    "512f7960534dcda22b000491"
                ]
            ],
            "_type": [
                [
                    "FacebookImageItem",
                    "FacebookImageItem"
                ],
                [
                    "FoursquareImageItem",
                    "FoursquareImageItem"
                ],
                [
                    "Image",
                    "Image"
                ],
                [
                    "InstagramItem",
                    "InstagramItem"
                ],
                [
                    "TwitterImageItem",
                    "TwitterImageItem"
                ]
            ],
            "when_tz": [
                [
                    {
                        "$minElement": 1
                    },
                    {
                        "$maxElement": 1
                    }
                ]
            ]
        }
    },
    {
        "cursor": "BasicCursor",
        "n": 0,
        "nscannedObjects": 15097,
        "nscanned": 15097,
        "indexBounds": {}
    }
],
"server": ""
}

知道如何让它达到索引吗？

4

1 回答 1

2

MongoDB 的文档中有一条关于索引的说明：

  • 对于使用 $or 运算符的查询，$or 查询的每个子句并行执行，并且每个子句都可以使用不同的索引。
  • 对于使用 sort() 方法并使用 $or 运算符的查询，查询不能使用 $or 字段上的索引。

尝试用另一种形式重写您的查询。我想知道您的查询中 $or 背后的要求是什么。

您可以尝试使用$hint来强制使用您的索引。将它与 $explain 结合使用，看看它是否适合您。

我在控制台中运行了您的查询并创建了一个包含 3 个字段的索引。使用提示和解释给了我以下输出，它告诉我索引被使用了 3 次查询被执行（每个 $ 或因为那些并行运行）查询：

db.stack.find(
{"_id":"512f7960534dcda22b000491", 
"_type":{"$in":["FacebookImageItem", "FoursquareImageItem", "InstagramItem", "TwitterImageItem", "Image"]},
"$or":
[
{"when_tz":{"$gte":ISODate("2010-06-24T04:00:00.000Z"), "$lt":ISODate("2010-06-25T04:00:00.000Z")}},
{"when_tz":{"$gte":ISODate("2011-06-24T04:00:00.000Z"), "$lt":ISODate("2011-06-25T04:00:00.000Z")}}, 
{"when_tz":{"$gte":ISODate("2012-06-24T04:00:00.000Z"), "$lt":ISODate("2012-06-25T04:00:00.000Z")}}
]

}
).hint("_id_1__type_1_when_tz_1").explain()

{
    "clauses" : [
            {
                    "cursor" : "BtreeCursor _id_1__type_1_when_tz_1 multi",
                    "nscanned" : 1,
                    "nscannedObjects" : 1,
                    "n" : 1,
                    "millis" : 0,
                    "nYields" : 0,
                    "nChunkSkips" : 0,
                    "isMultiKey" : false,
                    "indexOnly" : false,
                    "indexBounds" : {
                            "_id" : [
                                    [
                                            "512f7960534dcda22b000491",
                                            "512f7960534dcda22b000491"
                                    ]
                            ],
                            "_type" : [
                                    [
                                            "FacebookImageItem",
                                            "FacebookImageItem"
                                    ],
                                    [
                                            "FoursquareImageItem",
                                            "FoursquareImageItem"
                                    ],
                                    [
                                            "Image",
                                            "Image"
                                    ],
                                    [
                                            "InstagramItem",
                                            "InstagramItem"
                                    ],
                                    [
                                            "TwitterImageItem",
                                            "TwitterImageItem"
                                    ]
                            ],
                            "when_tz" : [
                                    [
                                            ISODate("2010-06-24T04:00:00Z"),
                                            ISODate("2010-06-25T04:00:00Z")
                                    ]
                            ]
                    }
            },
            {
                    "cursor" : "BtreeCursor _id_1__type_1_when_tz_1 multi",
                    "nscanned" : 0,
                    "nscannedObjects" : 0,
                    "n" : 0,
                    "millis" : 1,
                    "nYields" : 0,
                    "nChunkSkips" : 0,
                    "isMultiKey" : false,
                    "indexOnly" : false,
                    "indexBounds" : {
                            "_id" : [
                                    [
                                            "512f7960534dcda22b000491",
                                            "512f7960534dcda22b000491"
                                    ]
                            ],
                            "_type" : [
                                    [
                                            "FacebookImageItem",
                                            "FacebookImageItem"
                                    ],
                                    [
                                            "FoursquareImageItem",
                                            "FoursquareImageItem"
                                    ],
                                    [
                                            "Image",
                                            "Image"
                                    ],
                                    [
                                            "InstagramItem",
                                            "InstagramItem"
                                    ],
                                    [
                                            "TwitterImageItem",
                                            "TwitterImageItem"
                                    ]
                            ],
                            "when_tz" : [
                                    [
                                            ISODate("2011-06-24T04:00:00Z"),
                                            ISODate("2011-06-25T04:00:00Z")
                                    ]
                            ]
                    }
            },
            {
                    "cursor" : "BtreeCursor _id_1__type_1_when_tz_1 multi",
                    "nscanned" : 0,
                    "nscannedObjects" : 0,
                    "n" : 0,
                    "millis" : 16,
                    "nYields" : 0,
                    "nChunkSkips" : 0,
                    "isMultiKey" : false,
                    "indexOnly" : false,
                    "indexBounds" : {
                            "_id" : [
                                    [
                                            "512f7960534dcda22b000491",
                                            "512f7960534dcda22b000491"
                                    ]
                            ],
                            "_type" : [
                                    [
                                            "FacebookImageItem",
                                            "FacebookImageItem"
                                    ],
                                    [
                                            "FoursquareImageItem",
                                            "FoursquareImageItem"
                                    ],
                                    [
                                            "Image",
                                            "Image"
                                    ],
                                    [
                                            "InstagramItem",
                                            "InstagramItem"
                                    ],
                                    [
                                            "TwitterImageItem",
                                            "TwitterImageItem"
                                    ]
                            ],
                            "when_tz" : [
                                    [
                                            ISODate("2012-06-24T04:00:00Z"),
                                            ISODate("2012-06-25T04:00:00Z")
                                    ]
                            ]
                    }
            }
    ],
    "nscanned" : 1,
    "nscannedObjects" : 1,
    "n" : 1,
    "millis" : 16
}
于 2013-06-24T22:17:23.433 回答