Object Storage Service:MetaSearch

O código a seguir mostra como ativar o recurso de gerenciamento de metadados de um bucket específico. Após a ativação, o OSS cria uma biblioteca de índices de metadados para o bucket e gera índices para todos os objetos armazenados. Com a biblioteca criada, o OSS varre os objetos incrementais do bucket quase em tempo real e cria índices de metadados para eles.

package main

import (
	"context"
	"flag"   
	"log"     

	"github.com/aliyun/alibabacloud-oss-go-sdk-v2/oss"          
	"github.com/aliyun/alibabacloud-oss-go-sdk-v2/oss/credentials" 
)

var (
	region     string // Specify a variable to store the region information obtained from the command lines.
	bucketName string // Specify a variable to store the bucket name obtained from the command lines.
)

// The init function is executed before the main function to initialize the program.
func init() {
	// Use a command line parameter to specify the region.
	flag.StringVar(&region, "region", "", "The region in which the bucket is located.")
	// Use a command line parameter to specify the bucket name.
	flag.StringVar(&bucketName, "bucket", "", "The name of the bucket.")
}

func main() {
	flag.Parse() // Parse command line parameters.

	// Check if the bucket name is specified. If not, the program outputs default parameters and terminates.
	if len(bucketName) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, bucket name required") // Log the error message and terminate the program.
	}

	// Check whether the region is specified. If the region is not specified, output the default parameters and exit the program.
	if len(region) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, region required") // Log the error message and terminate the program.
	}

	// Create and configure a client and use environment variables to pass the credential provider.
	cfg := oss.LoadDefaultConfig().
		WithCredentialsProvider(credentials.NewEnvironmentVariableCredentialsProvider()).
		WithRegion(region)

	client := oss.NewClient(cfg) // Use the client configurations to create a new OSSClient instance.

	// Create an OpenMetaQuery request to enable the metadata management feature for a specific bucket.
	request := &oss.OpenMetaQueryRequest{
		Bucket: oss.Ptr(bucketName), // Specify the name of the bucket.
	}
	result, err := client.OpenMetaQuery(context.TODO(), request) // Execute the request to enable the metadata management feature for the bucket.
	if err != nil {
		log.Fatalf("failed to open meta query %v", err) // If an error occurs, record the error message and terminate the program.
	}

	log.Printf("open meta query result:%#v\n", result) // Display the result.
}

O código a seguir mostra como consultar as informações da biblioteca de índices de metadados de um bucket.

package main

import (
	"context" 
	"flag"   
	"log"   

	"github.com/aliyun/alibabacloud-oss-go-sdk-v2/oss"
	"github.com/aliyun/alibabacloud-oss-go-sdk-v2/oss/credentials"
)

var (
	region     string // Specify a variable to store the region information obtained from the command lines.
	bucketName string // Specify a variable to store the bucket name obtained from the command lines.
)

// The init function is executed before the main function to initialize the program.
func init() {
	// Use a command line parameter to specify the region.
	flag.StringVar(&region, "region", "", "The region in which the bucket is located.")
	// Use a command line parameter to specify the bucket name.
	flag.StringVar(&bucketName, "bucket", "", "The name of the bucket.")
}

func main() {
	flag.Parse() // Parse command line parameters.

	// Check if the bucket name is specified. If not, the program outputs default parameters and terminates.
	if len(bucketName) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, bucket name required") // Log the error message and terminate the program.
	}

	// Check if the region is specified. If not, the program outputs default parameters and terminates.
	if len(region) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, region required") // Log the error message and terminate the program.
	}

	// Create and configure a client and use environment variables to pass the credential provider and the region.
	cfg := oss.LoadDefaultConfig().
		WithCredentialsProvider(credentials.NewEnvironmentVariableCredentialsProvider()).
		WithRegion(region)

	client := oss.NewClient(cfg) // Create a new OSSClient instance.

	// Create a GetMetaQueryStatus request to query information about the metadata index library of a specific bucket.
	request := &oss.GetMetaQueryStatusRequest{
		Bucket: oss.Ptr(bucketName), // Specify the name of the bucket.
	}
	result, err := client.GetMetaQueryStatus(context.TODO(), request) // Execute the query request.
	if err != nil {
		log.Fatalf("failed to get meta query status %v", err) // If an error occurs, record the error message and terminate the program.
	}

	log.Printf("get meta query status result:%#v\n", result)
}

O código a seguir mostra como usar o MetaSearch para consultar objetos que atendem a condições específicas e listar suas informações com base em campos e métodos de classificação definidos.

package main

import (
	"context"
	"flag"
	"fmt"
	"log"

	"github.com/aliyun/alibabacloud-oss-go-sdk-v2/oss"
	"github.com/aliyun/alibabacloud-oss-go-sdk-v2/oss/credentials"
)

var (
	region     string // Specify a variable to store the region information obtained from the command lines.
	bucketName string // Specify a variable to store the bucket name obtained from the command lines.
)

// The init function is executed before the main function to initialize the program.
func init() {
	// Use a command line parameter to specify the region. By default, the parameter is an empty string.
	flag.StringVar(&region, "region", "", "The region in which the bucket is located.")
	// Use a command line parameter to specify the bucket name. By default, the parameter is an empty string.
	flag.StringVar(&bucketName, "bucket", "", "The name of the bucket.")
}

func main() {
	flag.Parse() // Parse command line parameters.

	// Check if the bucket name is specified. If not, the program outputs default parameters and terminates.
	if len(bucketName) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, bucket name required")
	}

	// Check if the region is specified. If not, the program outputs default parameters and terminates.
	if len(region) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, region required")
	}

	// Create and configure a client and use environment variables to pass the credential provider and the region.
	cfg := oss.LoadDefaultConfig().
		WithCredentialsProvider(credentials.NewEnvironmentVariableCredentialsProvider()).
		WithRegion(region)

	client := oss.NewClient(cfg) // Use the client configurations to create a new OSSClient instance.

	// Create a DoMetaQuery request to query the objects that meet specific conditions.
	request := &oss.DoMetaQueryRequest{
		Bucket: oss.Ptr(bucketName), // Specify the name of the bucket.
		MetaQuery: &oss.MetaQuery{
			Query: oss.Ptr(`{"Field": "Size","Value": "1048576","Operation": "gt"}`), // Query objects whose size is larger than 1 MB.
			Sort:  oss.Ptr("Size"),                                                  // List the objects by size.
			Order: oss.Ptr(oss.MetaQueryOrderAsc),                                  // Sort the objects in ascending order.
		},
	}
	result, err := client.DoMetaQuery(context.TODO(), request) // Execute the request to query the objects that meet the preceding conditions.
	if err != nil {
		log.Fatalf("failed to do meta query %v", err)
	}

	// Display the token used to query data on the next page.
	fmt.Printf("NextToken:%s\n", *result.NextToken)

	// Traverse the returned results and display the details of each object.
	for _, file := range result.Files {
		fmt.Printf("File name: %s\n", *file.Filename)
		fmt.Printf("size: %d\n", file.Size)
		fmt.Printf("File Modified Time:%s\n", *file.FileModifiedTime)
		fmt.Printf("Oss Object Type:%s\n", *file.OSSObjectType)
		fmt.Printf("Oss Storage Class:%s\n", *file.OSSStorageClass)
		fmt.Printf("Object ACL:%s\n", *file.ObjectACL)
		fmt.Printf("ETag:%s\n", *file.ETag)
		fmt.Printf("Oss CRC64:%s\n", *file.OSSCRC64)
		if file.OSSTaggingCount != nil {
			fmt.Printf("Oss Tagging Count:%d\n", *file.OSSTaggingCount)
		}

		// Display the tags of the objects.
		for _, tagging := range file.OSSTagging {
			fmt.Printf("Oss Tagging Key:%s\n", *tagging.Key)
			fmt.Printf("Oss Tagging Value:%s\n", *tagging.Value)
		}

		// Display the user metadata.
		for _, userMeta := range file.OSSUserMeta {
			fmt.Printf("Oss User Meta Key:%s\n", *userMeta.Key)
			fmt.Printf("Oss User Meta Key Value:%s\n", *userMeta.Value)
		}
	}
}

O código a seguir mostra como desativar o recurso de gerenciamento de metadados de um bucket específico.

package main

import (
	"context"
	"flag"    
	"log"    

	"github.com/aliyun/alibabacloud-oss-go-sdk-v2/oss"          
	"github.com/aliyun/alibabacloud-oss-go-sdk-v2/oss/credentials" 
)

var (
	region     string // Specify a variable to store the region information obtained from the command lines.
	bucketName string // Specify a variable to store the bucket name obtained from the command lines.
)

// The init function is executed before the main function to initialize the program.
func init() {
	// Use a command line parameter to specify the region.
	flag.StringVar(&region, "region", "", "The region in which the bucket is located.")
	// Use a command line parameter to specify the bucket name.
	flag.StringVar(&bucketName, "bucket", "", "The name of the bucket.")
}

func main() {
	flag.Parse() // Parse command line parameters.

	// Check if the bucket name is specified. If not, the program outputs default parameters and terminates.
	if len(bucketName) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, bucket name required") // Log the error message and terminate the program.
	}

	// Check if the region is specified. If not, the program outputs default parameters and terminates.
	if len(region) == 0 {
		flag.PrintDefaults()
		log.Fatalf("invalid parameters, region required") // Log the error message and terminate the program.
	}

	// Create and configure a client and use environment variables to pass the credential provider and the region.
	cfg := oss.LoadDefaultConfig().
		WithCredentialsProvider(credentials.NewEnvironmentVariableCredentialsProvider()).
		WithRegion(region)

	client := oss.NewClient(cfg) // Create a new OSSClient instance.

	// Create a CloseMetaQuery request to disable the metadata management feature for the bucket.
	request := &oss.CloseMetaQueryRequest{
		Bucket: oss.Ptr(bucketName), // Specify the name of the bucket.
	}
	result, err := client.CloseMetaQuery(context.TODO(), request) // Execute the request.
	if err != nil {
		log.Fatalf("failed to close meta query %v", err) // If an error occurs, record the error message and exit the program.
	}

	log.Printf("close meta query result:%#v\n", result)
}