Question

我知道如何进行不区分大小写的搜索。

示例：

members.email：aaa@aaa.com但：

users.email：AAA@aaa.com

db.getCollection('members').aggregate([
{$lookup: {'from': 'users', 'localField': 'members.email', 'foreignField': 'email', 'as': 'users'}},
{$unwind: {path: '$users', preserveNullAndEmptyArrays: true}},
{$match : { users: { $exists: false } }},
]);

集合成员如下：

{
"_id" : ObjectId("5b439c02a5439e00568291fe"),
"members" : [ 
    {
        "email" : "aaa@gmail.com"
    }, 
    {
        "email" : "bbb@gmail.com"
    }, 
    {
        "email" : "ccc@gmail.com"
    }
],
"groupname" : "abuse",
"active" : true,
"createdAt" : ISODate("2018-07-09T17:31:46.098Z"),
"updatedAt" : ISODate("2018-07-09T17:31:46.098Z"),
"__v" : 0
}

集合member_user如下：

{
"_id" : ObjectId("5a7dfce545e13f0233b2e451"),
"email" : "AAA@gmail.com",
"__v" : 0
}

{
"_id" : ObjectId("5b43ac89bfd90aa9cc4a68c2"),
"email" : "bbb@gmail.com",
"__v" : 0
}

这是我使用的代码：

    db.getCollection('member').aggregate([
    {$unwind: "$members"},
    {$lookup: {'from': 'member_user', 'localField': 'members.email', 'foreignField': 'email', 'as': 'users'}},
    {$unwind: {path: '$users', preserveNullAndEmptyArrays: true}},
    {$match : { users: { $exists: false } }},
], 
{
    collation: {
        locale: 'en_US',
        strength: 1
    }
}
    );

当数据集较小时，速度始终非常快。但是我有24K成员和7K用户。就像我说的那样，当{$ match：{用户：{$ exists：true}}}时，速度还可以，但是当{$ match：{用户：{$ exists：false}}}}时，速度将近60倍。（1秒1分钟）

没有排序规则，速度总是很快的

Answer 1

您需要使用$toLower聚合将foreignField和db.collection.aggregate([ { "$unwind": "$members" }, { "$addFields": { "members.email": { "$toLower": "$members.email" }}}, { "$lookup": { "from": "users", "let": { "membersEmail": "$members.email" }, "pipeline": [ { "$addFields": { "email": { "$toLower": "$email" }}}, { "$match": { "$expr": { "$eq": [ "$email", "$$membersEmail" ] } } } ], "as": "members.email" }}, { "$unwind": "$members.email" }, { "$group": { "_id": "$_id", "groupname": { "$first": "$groupname" }, "active": { "$first": "$active" }, "members": { "$push": "$members.email" } }} ])转换为小写，然后才能轻松匹配字段。

sudo port upgrade qt59-qtdoc

$ lookup具有区分大小写的字段

1 个答案: