如何使用Java在MongoDB中删除索引？
在MongoDB中删除索引，您需要使用dropIndex()方法。
语法
db.COLLECTION_NAME.dropIndex({KEY:1})在Java中，可以使用dropIndex()方法删除索引，您需要将索引的类型（升序或降序）和在其上创建字段的名称传递给该方法。
dropIndex(Indexes.ascending("name"));示例
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoDatabase;
import com.mongodb.client.model.Indexes;
import org.bson.Document;
import com.mongodb.MongoClient;
public class DroppingIndex {
public static void main( String args[] ) {
//创建一个MongoDB客户端
MongoClient mongo = new MongoClient( "localhost" , 27017 );
//访问数据库
MongoDatabase database = mongo.getDatabase("myDatabase");
//创建一个集合
database.createCollection("sampleCollection");
//检索要在其上创建索引的集合
MongoCollection coll = database.getCollection("sampleCollection");
//创建索引
coll.createIndex(Indexes.ascending("age"));
coll.createIndex(Indexes.ascending("name"));
System.out.println("List of colections: ");
for (Document index : coll.listIndexes()) {
System.out.println(index.toJson());
}
//删除索引
coll = database.getCollection("sampleCollection");
coll.dropIndex(Indexes.ascending("name"));
System.out.println("List of colections after deleting one ");
for (Document index : coll.listIndexes()) {
System.out.println(index.toJson());
}
}
}输出结果
List of colections:
{"v": 2, "key": {"_id": 1}, "name": "_id_", "ns": "myDatabase.sampleCollection"}
{"v": 2, "key": {"age": 1}, "name": "age_1", "ns": "myDatabase.sampleCollection"}
{"v": 2, "key": {"name": 1}, "name": "name_1", "ns":
"myDatabase.sampleCollection"}
List of colections after deleting one
{"v": 2, "key": {"_id": 1}, "name": "_id_", "ns": "myDatabase.sampleCollection"}
{"v": 2, "key": {"age": 1}, "name": "age_1", "ns": "myDatabase.sampleCollection"}