英文:
How to create compound indexes in mongoDB using golang mongo-driver?
问题
我正在尝试在数据库中创建一个索引，但是CreateMany方法会在指定的列数组上为每个列创建索引。
但是我需要为一对列创建一个复合索引。
英文:
I am trying to create an index in the database, but, CreateMany creates indexes on individual columns on the array of columns specified.
But I require a compound index for a couple of columns
答案1
得分: 2
您可以使用值为mongo.IndexModel的索引来指定索引：
type IndexModel struct {// 描述应该用于索引的键的文档。它不能为nil。这必须是一个保持顺序的类型，如bson.D。不支持映射类型，如bson.M。请参阅https://docs.mongodb.com/manual/indexes/#indexes// 了解有效文档的示例。Keys interface{}// 用于创建索引的选项。Options *options.IndexOptions}
可索引的属性（或属性）在Keys字段中给出。它不一定必须包含一个单独的属性。根据其名称（Keys）和文档提示：它可以包含多个属性，并且由于顺序很重要，应该使用保持顺序的数据结构列出，例如bson.D。
下面是一个示例，创建了两个复合索引，第一个索引使用prop1、prop2和prop3，第二个索引使用prop4和prop5。
ctx := context.Background()c := db.Collection("collname")_, err = c.Indexes().CreateMany(ctx, []mongo.IndexModel{// prop1, prop2, prop3{Keys: bson.D{{Key: "prop1", Value: 1}, // prop1升序{Key: "prop2", Value: 1}, // prop2升序{Key: "prop3", Value: -1}, // prop3降序},},// prop4, prop5{Keys: bson.D{{Key: "prop4", Value: 1}, // prop4升序{Key: "prop5", Value: 1}, // prop5升序},},})if err != nil {log.Printf("Failed to create indices: %v", err)}
英文:
You specify an index with a value of mongo.IndexModel:
type IndexModel struct {// A document describing which keys should be used for the index. It cannot be nil. This must be an order-preserving// type such as bson.D. Map types such as bson.M are not valid. See https://docs.mongodb.com/manual/indexes/#indexes// for examples of valid documents.Keys interface{}// The options to use to create the index.Options *options.IndexOptions}
The indexable property (or properties) are given in the Keys field. It does not necessary have to contain a single property. As its name (Keys) and doc hits: it may contain multiple properties, and since order matters, it should be listed with a data structure that preservers order, such as bson.D.
Here's an example creating 2 compound indices, first one using prop1, prop2 and prop3, the second one using prop4 and prop4.
ctx := context.Background()c := db.Collection("collname")_, err = c.Indexes().CreateMany(ctx, []mongo.IndexModel{// prop1, prop2, prop3{Keys: bson.D{{Key: "prop1", Value: 1}, // prop1 asc{Key: "prop2", Value: 1}, // prop2 asc{Key: "prop3", Value: -1}, // prop3 desc},},// prop4, prop5{Keys: bson.D{{Key: "prop4", Value: 1}, // prop4 asc{Key: "prop5", Value: 1}, // prop5 asc},},})if err != nil {log.Printf("Failed to create indices: %v", err)}
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