【发布时间】：2017-10-16 08:41:42
【问题描述】：
尝试按两个字段排序，优先考虑第一个 - 但在大多数情况下，似乎优先考虑第二个（姓氏）。有时，它可以正常工作 - 不确定是什么导致了这种变化。
使用 Robo3t 作为客户端，连接相同的数据库，同样的命令也能正常工作。
运行 Flask 并使用 Mongoengine，代码如下：
pipeline = [{"$sort": {"importance": -1, "lastName": 1}}, {"$match": {"visible": True, "editionId": "2017"}},
{"$project": {'firstName': 1, 'lastName': 1, 'biography': 1, 'position': 1, 'workAt': 1, '_id': 0,
"imageUrl": 1}}]
doc = Speakers.objects.aggregate(*pipeline)
在 Robo3t 中，相同的代码（'True' 变为 'true' 除外）：
db.getCollection('speakers').aggregate([{"$sort": {"importance": -1, "lastName": 1}}, {"$match": {"visible": true, "editionId": "2017"}},
{"$project": {'firstName': 1, 'lastName': 1, 'biography': 1, 'position': 1, 'workAt': 1, '_id': 0,
"imageUrl": 1}}], {"collation": {"locale": "en"}}
)
mongodb (3.4.9) 上的索引如下所示：
> db.speakers.getIndexes()
[
{
"v" : 1,
"key" : {
"_id" : 1
},
"name" : "_id_",
"ns" : "website_v3.speakers"
}
]
使用数据库版本 v3.4.9
我什至尝试过为重要性创建一个索引（排序规则），但结果完全一样。首先它起作用，然后它不起作用。
欢迎任何想法！
编辑：
flask_mongoengine 似乎弄乱了 $sort 和 $project 的顺序。
mongo
> db.system.profile.find().pretty()
{
"op" : "query",
"ns" : "website_v3.system.profile",
"query" : {
"find" : "system.profile",
"filter" : {
}
},
"keysExamined" : 0,
"docsExamined" : 0,
"cursorExhausted" : true,
"numYield" : 0,
"locks" : {
"Global" : {
"acquireCount" : {
"r" : NumberLong(2)
}
},
"Database" : {
"acquireCount" : {
"r" : NumberLong(1)
}
},
"Collection" : {
"acquireCount" : {
"r" : NumberLong(1)
}
}
},
"nreturned" : 0,
"responseLength" : 98,
"protocol" : "op_command",
"millis" : 0,
"planSummary" : "COLLSCAN",
"execStats" : {
"stage" : "COLLSCAN",
"nReturned" : 0,
"executionTimeMillisEstimate" : 0,
"works" : 2,
"advanced" : 0,
"needTime" : 1,
"needYield" : 0,
"saveState" : 0,
"restoreState" : 0,
"isEOF" : 1,
"invalidates" : 0,
"direction" : "forward",
"docsExamined" : 0
},
"ts" : ISODate("2017-10-19T20:55:30.415Z"),
}
{
"op" : "command",
"ns" : "website_v3.speakers",
"command" : {
"aggregate" : "speakers",
"pipeline" : [
{
"$match" : {
"visible" : true,
"editionId" : "2017"
}
},
{
"$sort" : {
"lastName" : 1,
"importance" : -1
}
},
{
"$project" : {
"firstName" : 1,
"position" : 1,
"biography" : 1,
"workAt" : 1,
"imageUrl" : 1,
"_id" : 0,
"lastName" : 1
}
}
],
"cursor" : {
}
},
"cursorid" : 168077246844,
"keysExamined" : 0,
"docsExamined" : 541,
"hasSortStage" : true,
"numYield" : 4,
"locks" : {
"Global" : {
"acquireCount" : {
"r" : NumberLong(16)
}
},
"Database" : {
"acquireCount" : {
"r" : NumberLong(8)
}
},
"Collection" : {
"acquireCount" : {
"r" : NumberLong(7)
}
}
},
"nreturned" : 101,
"responseLength" : 157635,
"protocol" : "op_query",
"millis" : 2,
"planSummary" : "COLLSCAN",
"ts" : ISODate("2017-10-19T20:55:57.691Z"),
}
{
"op" : "getmore",
"ns" : "website_v3.speakers",
"query" : {
"getMore" : NumberLong("168077246844"),
"collection" : "speakers"
},
"originatingCommand" : {
"aggregate" : "speakers",
"pipeline" : [
{
"$match" : {
"visible" : true,
"editionId" : "2017"
}
},
{
"$sort" : {
"lastName" : 1,
"importance" : -1
}
},
{
"$project" : {
"firstName" : 1,
"position" : 1,
"biography" : 1,
"workAt" : 1,
"imageUrl" : 1,
"_id" : 0,
"lastName" : 1
}
}
],
"cursor" : {
}
},
"cursorid" : 168077246844,
"keysExamined" : 0,
"docsExamined" : 0,
"hasSortStage" : true,
"cursorExhausted" : true,
"numYield" : 0,
"locks" : {
"Global" : {
"acquireCount" : {
"r" : NumberLong(4)
}
},
"Database" : {
"acquireCount" : {
"r" : NumberLong(2)
}
},
"Collection" : {
"acquireCount" : {
"r" : NumberLong(2)
}
}
},
"nreturned" : 204,
"responseLength" : 303603,
"protocol" : "op_query",
"millis" : 0,
"planSummary" : "COLLSCAN",
"ts" : ISODate("2017-10-19T20:55:57.702Z"),
}
【问题讨论】：
标签： python mongodb mongoengine flask-mongoengine