# Select API Quickstart Guide [![Slack](https://slack.min.io/slack?type=svg)](https://slack.min.io)

Traditional retrieval of objects is always as whole entities, i.e GetObject for a 5 GiB object, will always return 5 GiB of data. S3 Select API allows us to retrieve a subset of data by using simple SQL expressions. By using Select API to retrieve only the data needed by the application, drastic performance improvements can be achieved.

			Effect:    string(policy.Allow),
			Principal: miniogopolicy.User{AWS: set.CreateStringSet("*")},
			Resources: set.CreateStringSet(policy.NewResource(bucketName + "/" + prefix).String()),
			Actions:   set.CreateStringSet("s3:GetObject"),
		},
	}
}

func TestPolicyToBucketAccessPolicy(t *testing.T) {
	case1Policy := &policy.BucketPolicy{
		Version: policy.DefaultVersion,
		Statements: []policy.BPStatement{

	// GCS storage decompresses a gzipped object by default and returns the data.
	// Refer to https://cloud.google.com/storage/docs/transcoding#decompressive_transcoding
	// Need to set `Accept-Encoding` header to `gzip` when issuing a GetObject call, to be able
	// to download the object in compressed state.
	// Calling ReadCompressed with true accomplishes that.
	object := gcs.client.Bucket(gcs.Bucket).Object(gcs.getDest(key)).ReadCompressed(true)

			HandlerFunc(s3APIMiddleware(api.GetObjectLegalHoldHandler)).
			Queries("legal-hold", "")
		// GetObject with lambda ARNs
		router.Methods(http.MethodGet).Path("/{object:.+}").
			HandlerFunc(s3APIMiddleware(api.GetObjectLambdaHandler, traceHdrsS3HFlag)).
			Queries("lambdaArn", "{lambdaArn:.*}")
		// GetObject
		router.Methods(http.MethodGet).Path("/{object:.+}").

		// If we resume to the same bucket, forward to last known item.
		b := tracker.getBucket()
		if b == bucket {
			forwardTo = tracker.getObject()
		}
		if b != "" {
			// Reset to where last bucket ended if resuming.
			tracker.resume()
		}
		tracker.setObject("")
		tracker.setBucket(bucket)
		// Heal current bucket again in case if it is failed
		// in the beginning of erasure set healing

	policy := "mypolicy"
	policyBytes := []byte(`{
 "Version": "2012-10-17",
 "Statement": [
  {
   "Effect": "Allow",
   "Action": [
    "s3:PutObject",
    "s3:GetObject",
    "s3:ListBucket"
   ],
   "Resource": [
    "arn:aws:s3:::BUCKET/*"
   ]
  }
 ]
}`)

	err := s.adm.AddCannedPolicy(ctx, policy, policyBytes)
	if err != nil {

```bash
helm install --set policies[0].name=mypolicy,policies[0].statements[0].resources[0]='arn:aws:s3:::bucket1',policies[0].statements[0].actions[0]='s3:ListBucket',policies[0].statements[0].actions[1]='s3:GetObject' minio/minio
```

Description of the configuration parameters used above -

- `policies[].name` - name of the policy to create, must be a string with length > 0

		return 0, nil, errors.New("bucket name cannot be empty")
	}

	clnt, err := driver.getMinIOClient(ctx)
	if err != nil {
		return 0, nil, err
	}

	opts := minio.GetObjectOptions{}
	obj, err := clnt.GetObject(context.Background(), bucket, object, opts)
	if err != nil {
		return 0, nil, err
	}
	defer func() {
		if err != nil && obj != nil {
			obj.Close()
		}
	}()

				return
			}
			for {
				if objCountPerThread[i] == j {
					j = 0
				}
				tmpObjName := pathJoin(objNamePrefix, fmt.Sprintf("%d/%d", i, j))
				t := time.Now()

				r, _, _, err := c.GetObject(downloadsCtx, opts.bucketName, tmpObjName, gopts)
				if err != nil {
					errResp, ok := err.(minio.ErrorResponse)
					if ok && errResp.StatusCode == http.StatusNotFound {
						continue
					}

	if bucket == "" {
		return nil, errors.New("bucket name cannot be empty")
	}

	clnt, err := f.getMinIOClient()
	if err != nil {
		return nil, err
	}

	obj, err := clnt.GetObject(context.Background(), bucket, object, minio.GetObjectOptions{})
	if err != nil {
		return nil, err
	}

	_, err = obj.Stat()
	if err != nil {
		return nil, err
	}

	return obj, nil
}