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Version: Stable-3.1

Delta Lake catalog

A Delta Lake catalog is a kind of external catalog that enables you to query data from Delta Lake without ingestion.

Also, you can directly transform and load data from Delta Lake by using INSERT INTO based on Delta Lake catalogs. StarRocks supports Delta Lake catalogs from v2.5 onwards.

To ensure successful SQL workloads on your Delta Lake cluster, your StarRocks cluster must be able to access the storage system and metastore of your Delta Lake cluster. StarRocks supports the following storage systems and metastores:

  • Distributed file system (HDFS) or object storage like AWS S3, Microsoft Azure Storage, Google GCS, or other S3-compatible storage system (for example, MinIO)

  • Metastore like Hive metastore or AWS Glue

    NOTE

    If you choose AWS S3 as storage, you can use HMS or AWS Glue as metastore. If you choose any other storage system, you can only use HMS as metastore.

Usage notes

  • The file format of Delta Lake that StarRocks supports is Parquet. Parquet files support the following compression formats: SNAPPY, LZ4, ZSTD, GZIP, and NO_COMPRESSION.
  • The data types of Delta Lake that StarRocks does not support are MAP and STRUCT.

Integration preparations

Before you create a Delta Lake catalog, make sure your StarRocks cluster can integrate with the storage system and metastore of your Delta Lake cluster.

AWS IAM

If your Delta Lake cluster uses AWS S3 as storage or AWS Glue as metastore, choose your suitable authentication method and make the required preparations to ensure that your StarRocks cluster can access the related AWS cloud resources.

The following authentication methods are recommended:

  • Instance profile
  • Assumed role
  • IAM user

Of the above-mentioned three authentication methods, instance profile is the most widely used.

For more information, see Preparation for authentication in AWS IAM.

HDFS

If you choose HDFS as storage, configure your StarRocks cluster as follows:

  • (Optional) Set the username that is used to access your HDFS cluster and Hive metastore. By default, StarRocks uses the username of the FE and BE or CN processes to access your HDFS cluster and Hive metastore. You can also set the username by adding export HADOOP_USER_NAME="<user_name>" at the beginning of the fe/conf/hadoop_env.sh file of each FE and at the beginning of the be/conf/hadoop_env.sh file of each BE or the cn/conf/hadoop_env.sh file of each CN. After you set the username in these files, restart each FE and each BE or CN to make the parameter settings take effect. You can set only one username for each StarRocks cluster.

  • When you query Delta Lake data, the FEs and BEs or CNs of your StarRocks cluster use the HDFS client to access your HDFS cluster. In most cases, you do not need to configure your StarRocks cluster to achieve that purpose, and StarRocks starts the HDFS client using the default configurations. You need to configure your StarRocks cluster only in the following situations:

    • High availability (HA) is enabled for your HDFS cluster: Add the hdfs-site.xml file of your HDFS cluster to the $FE_HOME/conf path of each FE and to the $BE_HOME/conf path of each BE or the $CN_HOME/conf path of each CN.
    • View File System (ViewFs) is enabled for your HDFS cluster: Add the core-site.xml file of your HDFS cluster to the $FE_HOME/conf path of each FE and to the $BE_HOME/conf path of each BE or the $CN_HOME/conf path of each CN.

NOTE

If an error indicating an unknown host is returned when you send a query, you must add the mapping between the host names and IP addresses of your HDFS cluster nodes to the /etc/hosts path.

Kerberos authentication

If Kerberos authentication is enabled for your HDFS cluster or Hive metastore, configure your StarRocks cluster as follows:

  • Run the kinit -kt keytab_path principal command on each FE and each BE or CN to obtain Ticket Granting Ticket (TGT) from Key Distribution Center (KDC). To run this command, you must have the permissions to access your HDFS cluster and Hive metastore. Note that accessing KDC with this command is time-sensitive. Therefore, you need to use cron to run this command periodically.
  • Add JAVA_OPTS="-Djava.security.krb5.conf=/etc/krb5.conf" to the $FE_HOME/conf/fe.conf file of each FE and to the $BE_HOME/conf/be.conf file of each BE or the $CN_HOME/conf/cn.conf file of each CN. In this example, /etc/krb5.conf is the save path of the krb5.conf file. You can modify the path based on your needs.

Create a Delta Lake catalog

Syntax

CREATE EXTERNAL CATALOG <catalog_name>
[COMMENT <comment>]
PROPERTIES
(
"type" = "deltalake",
MetastoreParams,
StorageCredentialParams,
MetadataUpdateParams
)

Parameters

catalog_name

The name of the Delta Lake catalog. The naming conventions are as follows:

  • The name can contain letters, digits (0-9), and underscores (_). It must start with a letter.
  • The name is case-sensitive and cannot exceed 1023 characters in length.

comment

The description of the Delta Lake catalog. This parameter is optional.

type

The type of your data source. Set the value to deltalake.

MetastoreParams

A set of parameters about how StarRocks integrates with the metastore of your data source.

Hive metastore

If you choose Hive metastore as the metastore of your data source, configure MetastoreParams as follows:

"hive.metastore.type" = "hive",
"hive.metastore.uris" = "<hive_metastore_uri>"

NOTE

Before querying Delta Lake data, you must add the mapping between the host names and IP addresses of your Hive metastore nodes to the /etc/hosts path. Otherwise, StarRocks may fail to access your Hive metastore when you start a query.

The following table describes the parameter you need to configure in MetastoreParams.

ParameterRequiredDescription
hive.metastore.typeYesThe type of metastore that you use for your Delta Lake cluster. Set the value to hive.
hive.metastore.urisYesThe URI of your Hive metastore. Format: thrift://<metastore_IP_address>:<metastore_port>.
If high availability (HA) is enabled for your Hive metastore, you can specify multiple metastore URIs and separate them with commas (,), for example, "thrift://<metastore_IP_address_1>:<metastore_port_1>,thrift://<metastore_IP_address_2>:<metastore_port_2>,thrift://<metastore_IP_address_3>:<metastore_port_3>".
AWS Glue

If you choose AWS Glue as the metastore of your data source, which is supported only when you choose AWS S3 as storage, take one of the following actions:

  • To choose the instance profile-based authentication method, configure MetastoreParams as follows:

    "hive.metastore.type" = "glue",
    "aws.glue.use_instance_profile" = "true",
    "aws.glue.region" = "<aws_glue_region>"
  • To choose the assumed role-based authentication method, configure MetastoreParams as follows:

    "hive.metastore.type" = "glue",
    "aws.glue.use_instance_profile" = "true",
    "aws.glue.iam_role_arn" = "<iam_role_arn>",
    "aws.glue.region" = "<aws_glue_region>"
  • To choose the IAM user-based authentication method, configure MetastoreParams as follows:

    "hive.metastore.type" = "glue",
    "aws.glue.use_instance_profile" = "false",
    "aws.glue.access_key" = "<iam_user_access_key>",
    "aws.glue.secret_key" = "<iam_user_secret_key>",
    "aws.glue.region" = "<aws_s3_region>"

The following table describes the parameters you need to configure in MetastoreParams.

ParameterRequiredDescription
hive.metastore.typeYesThe type of metastore that you use for your Delta Lake cluster. Set the value to glue.
aws.glue.use_instance_profileYesSpecifies whether to enable the instance profile-based authentication method and the assumed role-based authentication method. Valid values: true and false. Default value: false.
aws.glue.iam_role_arnNoThe ARN of the IAM role that has privileges on your AWS Glue Data Catalog. If you use the assumed role-based authentication method to access AWS Glue, you must specify this parameter.
aws.glue.regionYesThe region in which your AWS Glue Data Catalog resides. Example: us-west-1.
aws.glue.access_keyNoThe access key of your AWS IAM user. If you use the IAM user-based authentication method to access AWS Glue, you must specify this parameter.
aws.glue.secret_keyNoThe secret key of your AWS IAM user. If you use the IAM user-based authentication method to access AWS Glue, you must specify this parameter.

For information about how to choose an authentication method for accessing AWS Glue and how to configure an access control policy in the AWS IAM Console, see Authentication parameters for accessing AWS Glue.

StorageCredentialParams

A set of parameters about how StarRocks integrates with your storage system. This parameter set is optional.

If you use HDFS as storage, you do not need to configure StorageCredentialParams.

If you use AWS S3, other S3-compatible storage system, Microsoft Azure Storage, or Google GCS as storage, you must configure StorageCredentialParams.

AWS S3

If you choose AWS S3 as storage for your Delta Lake cluster, take one of the following actions:

  • To choose the instance profile-based authentication method, configure StorageCredentialParams as follows:

    "aws.s3.use_instance_profile" = "true",
    "aws.s3.region" = "<aws_s3_region>"
  • To choose the assumed role-based authentication method, configure StorageCredentialParams as follows:

    "aws.s3.use_instance_profile" = "true",
    "aws.s3.iam_role_arn" = "<iam_role_arn>",
    "aws.s3.region" = "<aws_s3_region>"
  • To choose the IAM user-based authentication method, configure StorageCredentialParams as follows:

    "aws.s3.use_instance_profile" = "false",
    "aws.s3.access_key" = "<iam_user_access_key>",
    "aws.s3.secret_key" = "<iam_user_secret_key>",
    "aws.s3.region" = "<aws_s3_region>"

The following table describes the parameters you need to configure in StorageCredentialParams.

ParameterRequiredDescription
aws.s3.use_instance_profileYesSpecifies whether to enable the instance profile-based authentication method and the assumed role-based authentication method. Valid values: true and false. Default value: false.
aws.s3.iam_role_arnNoThe ARN of the IAM role that has privileges on your AWS S3 bucket. If you use the assumed role-based authentication method to access AWS S3, you must specify this parameter.
aws.s3.regionYesThe region in which your AWS S3 bucket resides. Example: us-west-1.
aws.s3.access_keyNoThe access key of your IAM user. If you use the IAM user-based authentication method to access AWS S3, you must specify this parameter.
aws.s3.secret_keyNoThe secret key of your IAM user. If you use the IAM user-based authentication method to access AWS S3, you must specify this parameter.

For information about how to choose an authentication method for accessing AWS S3 and how to configure an access control policy in AWS IAM Console, see Authentication parameters for accessing AWS S3.

S3-compatible storage system

Delta Lake catalogs support S3-compatible storage systems from v2.5 onwards.

If you choose an S3-compatible storage system, such as MinIO, as storage for your Delta Lake cluster, configure StorageCredentialParams as follows to ensure a successful integration:

"aws.s3.enable_ssl" = "false",
"aws.s3.enable_path_style_access" = "true",
"aws.s3.endpoint" = "<s3_endpoint>",
"aws.s3.access_key" = "<iam_user_access_key>",
"aws.s3.secret_key" = "<iam_user_secret_key>"

The following table describes the parameters you need to configure in StorageCredentialParams.

ParameterRequiredDescription
aws.s3.enable_sslYesSpecifies whether to enable SSL connection.
Valid values: true and false. Default value: true.
aws.s3.enable_path_style_accessYesSpecifies whether to enable path-style access.
Valid values: true and false. Default value: false. For MinIO, you must set the value to true.
Path-style URLs use the following format: https://s3.<region_code>.amazonaws.com/<bucket_name>/<key_name>. For example, if you create a bucket named DOC-EXAMPLE-BUCKET1 in the US West (Oregon) Region, and you want to access the alice.jpg object in that bucket, you can use the following path-style URL: https://s3.us-west-2.amazonaws.com/DOC-EXAMPLE-BUCKET1/alice.jpg.
aws.s3.endpointYesThe endpoint that is used to connect to your S3-compatible storage system instead of AWS S3.
aws.s3.access_keyYesThe access key of your IAM user.
aws.s3.secret_keyYesThe secret key of your IAM user.
Microsoft Azure Storage

Delta Lake catalogs support Microsoft Azure Storage from v3.0 onwards.

Azure Blob Storage

If you choose Blob Storage as storage for your Delta Lake cluster, take one of the following actions:

  • To choose the Shared Key authentication method, configure StorageCredentialParams as follows:

    "azure.blob.storage_account" = "<storage_account_name>",
    "azure.blob.shared_key" = "<storage_account_shared_key>"

    The following table describes the parameters you need to configure in StorageCredentialParams.

    ParameterRequiredDescription
    azure.blob.storage_accountYesThe username of your Blob Storage account.
    azure.blob.shared_keyYesThe shared key of your Blob Storage account.
  • To choose the SAS Token authentication method, configure StorageCredentialParams as follows:

    "azure.blob.storage_account" = "<storage_account_name>",
    "azure.blob.container" = "<container_name>",
    "azure.blob.sas_token" = "<storage_account_SAS_token>"

    The following table describes the parameters you need to configure in StorageCredentialParams.

    ParameterRequiredDescription
    azure.blob.storage_accountYesThe username of your Blob Storage account.
    azure.blob.containerYesThe name of the blob container that stores your data.
    azure.blob.sas_tokenYesThe SAS token that is used to access your Blob Storage account.
Azure Data Lake Storage Gen2

If you choose Data Lake Storage Gen2 as storage for your Delta Lake cluster, take one of the following actions:

  • To choose the Managed Identity authentication method, configure StorageCredentialParams as follows:

    "azure.adls2.oauth2_use_managed_identity" = "true",
    "azure.adls2.oauth2_tenant_id" = "<service_principal_tenant_id>",
    "azure.adls2.oauth2_client_id" = "<service_client_id>"

    The following table describes the parameters you need to configure in StorageCredentialParams.

    ParameterRequiredDescription
    azure.adls2.oauth2_use_managed_identityYesSpecifies whether to enable the Managed Identity authentication method. Set the value to true.
    azure.adls2.oauth2_tenant_idYesThe ID of the tenant whose data you want to access.
    azure.adls2.oauth2_client_idYesThe client (application) ID of the managed identity.
  • To choose the Shared Key authentication method, configure StorageCredentialParams as follows:

    "azure.adls2.storage_account" = "<storage_account_name>",
    "azure.adls2.shared_key" = "<storage_account_shared_key>"

    The following table describes the parameters you need to configure in StorageCredentialParams.

    ParameterRequiredDescription
    azure.adls2.storage_accountYesThe username of your Data Lake Storage Gen2 storage account.
    azure.adls2.shared_keyYesThe shared key of your Data Lake Storage Gen2 storage account.
  • To choose the Service Principal authentication method, configure StorageCredentialParams as follows:

    "azure.adls2.oauth2_client_id" = "<service_client_id>",
    "azure.adls2.oauth2_client_secret" = "<service_principal_client_secret>",
    "azure.adls2.oauth2_client_endpoint" = "<service_principal_client_endpoint>"

    The following table describes the parameters you need to configure in StorageCredentialParams.

    ParameterRequiredDescription
    azure.adls2.oauth2_client_idYesThe client (application) ID of the service principal.
    azure.adls2.oauth2_client_secretYesThe value of the new client (application) secret created.
    azure.adls2.oauth2_client_endpointYesThe OAuth 2.0 token endpoint (v1) of the service principal or application.
Azure Data Lake Storage Gen1

If you choose Data Lake Storage Gen1 as storage for your Delta Lake cluster, take one of the following actions:

  • To choose the Managed Service Identity authentication method, configure StorageCredentialParams as follows:

    "azure.adls1.use_managed_service_identity" = "true"

    The following table describes the parameters you need to configure in StorageCredentialParams.

    ParameterRequiredDescription
    azure.adls1.use_managed_service_identityYesSpecifies whether to enable the Managed Service Identity authentication method. Set the value to true.
  • To choose the Service Principal authentication method, configure StorageCredentialParams as follows:

    "azure.adls1.oauth2_client_id" = "<application_client_id>",
    "azure.adls1.oauth2_credential" = "<application_client_credential>",
    "azure.adls1.oauth2_endpoint" = "<OAuth_2.0_authorization_endpoint_v2>"

    The following table describes the parameters you need to configure in StorageCredentialParams.

    ParameterRequiredDescription
    azure.adls1.oauth2_client_idYesThe client (application) ID of the service principal.
    azure.adls1.oauth2_credentialYesThe value of the new client (application) secret created.
    azure.adls1.oauth2_endpointYesThe OAuth 2.0 token endpoint (v1) of the service principal or application.
Google GCS

Delta Lake catalogs support Google GCS from v3.0 onwards.

If you choose Google GCS as storage for your Delta Lake cluster, take one of the following actions:

  • To choose the VM-based authentication method, configure StorageCredentialParams as follows:

    "gcp.gcs.use_compute_engine_service_account" = "true"

    The following table describes the parameters you need to configure in StorageCredentialParams.

    ParameterDefault valueValue exampleDescription
    gcp.gcs.use_compute_engine_service_accountfalsetrueSpecifies whether to directly use the service account that is bound to your Compute Engine.
  • To choose the service account-based authentication method, configure StorageCredentialParams as follows:

    "gcp.gcs.service_account_email" = "<google_service_account_email>",
    "gcp.gcs.service_account_private_key_id" = "<google_service_private_key_id>",
    "gcp.gcs.service_account_private_key" = "<google_service_private_key>",

    The following table describes the parameters you need to configure in StorageCredentialParams.

    ParameterDefault valueValue exampleDescription
    gcp.gcs.service_account_email"""user@hello.iam.gserviceaccount.com"The email address in the JSON file generated at the creation of the service account.
    gcp.gcs.service_account_private_key_id"""61d257bd8479547cb3e04f0b9b6b9ca07af3b7ea"The private key ID in the JSON file generated at the creation of the service account.
    gcp.gcs.service_account_private_key"""-----BEGIN PRIVATE KEY----xxxx-----END PRIVATE KEY-----\n"The private key in the JSON file generated at the creation of the service account.
  • To choose the impersonation-based authentication method, configure StorageCredentialParams as follows:

    • Make a VM instance impersonate a service account:

      "gcp.gcs.use_compute_engine_service_account" = "true",
      "gcp.gcs.impersonation_service_account" = "<assumed_google_service_account_email>"

      The following table describes the parameters you need to configure in StorageCredentialParams.

      ParameterDefault valueValue exampleDescription
      gcp.gcs.use_compute_engine_service_accountfalsetrueSpecifies whether to directly use the service account that is bound to your Compute Engine.
      gcp.gcs.impersonation_service_account"""hello"The service account that you want to impersonate.
    • Make a service account (temporarily named as meta service account) impersonate another service account (temporarily named as data service account):

      "gcp.gcs.service_account_email" = "<google_service_account_email>",
      "gcp.gcs.service_account_private_key_id" = "<meta_google_service_account_email>",
      "gcp.gcs.service_account_private_key" = "<meta_google_service_account_email>",
      "gcp.gcs.impersonation_service_account" = "<data_google_service_account_email>"

      The following table describes the parameters you need to configure in StorageCredentialParams.

      ParameterDefault valueValue exampleDescription
      gcp.gcs.service_account_email"""user@hello.iam.gserviceaccount.com"The email address in the JSON file generated at the creation of the meta service account.
      gcp.gcs.service_account_private_key_id"""61d257bd8479547cb3e04f0b9b6b9ca07af3b7ea"The private key ID in the JSON file generated at the creation of the meta service account.
      gcp.gcs.service_account_private_key"""-----BEGIN PRIVATE KEY----xxxx-----END PRIVATE KEY-----\n"The private key in the JSON file generated at the creation of the meta service account.
      gcp.gcs.impersonation_service_account"""hello"The data service account that you want to impersonate.

MetadataUpdateParams

A set of parameters about how StarRocks updates the cached metadata of Delta Lake. This parameter set is optional.

StarRocks implements the automatic asynchronous update policy by default.

In most cases, you can ignore MetadataUpdateParams and do not need to tune the policy parameters in it, because the default values of these parameters already provide you with an out-of-the-box performance.

However, if the frequency of data updates in Delta Lake is high, you can tune these parameters to further optimize the performance of automatic asynchronous updates.

NOTE

In most cases, if your Delta Lake data is updated at a granularity of 1 hour or less, the data update frequency is considered high.

ParameterRequiredDescription
enable_metastore_cacheNoSpecifies whether StarRocks caches the metadata of Delta Lake tables. Valid values: true and false. Default value: true. The value true enables the cache, and the value false disables the cache.
enable_remote_file_cacheNoSpecifies whether StarRocks caches the metadata of the underlying data files of Delta Lake tables or partitions. Valid values: true and false. Default value: true. The value true enables the cache, and the value false disables the cache.
metastore_cache_refresh_interval_secNoThe time interval at which StarRocks asynchronously updates the metadata of Delta Lake tables or partitions cached in itself. Unit: seconds. Default value: 7200, which is 2 hours.
remote_file_cache_refresh_interval_secNoThe time interval at which StarRocks asynchronously updates the metadata of the underlying data files of Delta Lake tables or partitions cached in itself. Unit: seconds. Default value: 60.
metastore_cache_ttl_secNoThe time interval at which StarRocks automatically discards the metadata of Delta Lake tables or partitions cached in itself. Unit: seconds. Default value: 86400, which is 24 hours.
remote_file_cache_ttl_secNoThe time interval at which StarRocks automatically discards the metadata of the underlying data files of Delta Lake tables or partitions cached in itself. Unit: seconds. Default value: 129600, which is 36 hours.

Examples

The following examples create a Delta Lake catalog named deltalake_catalog_hms or deltalake_catalog_glue, depending on the type of metastore you use, to query data from your Delta Lake cluster.

HDFS

If you use HDFS as storage, run a command like below:

CREATE EXTERNAL CATALOG deltalake_catalog_hms
PROPERTIES
(
"type" = "deltalake",
"hive.metastore.type" = "hive",
"hive.metastore.uris" = "thrift://xx.xx.xx.xx:9083"
);

AWS S3

If you choose instance profile-based credential
  • If you use Hive metastore in your Delta Lake cluster, run a command like below:

    CREATE EXTERNAL CATALOG deltalake_catalog_hms
    PROPERTIES
    (
    "type" = "deltalake",
    "hive.metastore.type" = "hive",
    "hive.metastore.uris" = "thrift://xx.xx.xx.xx:9083",
    "aws.s3.use_instance_profile" = "true",
    "aws.s3.region" = "us-west-2"
    );
  • If you use AWS Glue in your Amazon EMR Delta Lake cluster, run a command like below:

    CREATE EXTERNAL CATALOG deltalake_catalog_glue
    PROPERTIES
    (
    "type" = "deltalake",
    "hive.metastore.type" = "glue",
    "aws.glue.use_instance_profile" = "true",
    "aws.glue.region" = "us-west-2",
    "aws.s3.use_instance_profile" = "true",
    "aws.s3.region" = "us-west-2"
    );
If you choose assumed role-based credential
  • If you use Hive metastore in your Delta Lake cluster, run a command like below:

    CREATE EXTERNAL CATALOG deltalake_catalog_hms
    PROPERTIES
    (
    "type" = "deltalake",
    "hive.metastore.type" = "hive",
    "hive.metastore.uris" = "thrift://xx.xx.xx.xx:9083",
    "aws.s3.use_instance_profile" = "true",
    "aws.s3.iam_role_arn" = "arn:aws:iam::081976408565:role/test_s3_role",
    "aws.s3.region" = "us-west-2"
    );
  • If you use AWS Glue in your Amazon EMR Delta Lake cluster, run a command like below:

    CREATE EXTERNAL CATALOG deltalake_catalog_glue
    PROPERTIES
    (
    "type" = "deltalake",
    "hive.metastore.type" = "glue",
    "aws.glue.use_instance_profile" = "true",
    "aws.glue.iam_role_arn" = "arn:aws:iam::081976408565:role/test_glue_role",
    "aws.glue.region" = "us-west-2",
    "aws.s3.use_instance_profile" = "true",
    "aws.s3.iam_role_arn" = "arn:aws:iam::081976408565:role/test_s3_role",
    "aws.s3.region" = "us-west-2"
    );
If you choose IAM user-based credential
  • If you use Hive metastore in your Delta Lake cluster, run a command like below:

    CREATE EXTERNAL CATALOG deltalake_catalog_hms
    PROPERTIES
    (
    "type" = "deltalake",
    "hive.metastore.type" = "hive",
    "hive.metastore.uris" = "thrift://xx.xx.xx.xx:9083",
    "aws.s3.use_instance_profile" = "false",
    "aws.s3.access_key" = "<iam_user_access_key>",
    "aws.s3.secret_key" = "<iam_user_access_key>",
    "aws.s3.region" = "us-west-2"
    );
  • If you use AWS Glue in your Amazon EMR Delta Lake cluster, run a command like below:

    CREATE EXTERNAL CATALOG deltalake_catalog_glue
    PROPERTIES
    (
    "type" = "deltalake",
    "hive.metastore.type" = "glue",
    "aws.glue.use_instance_profile" = "false",
    "aws.glue.access_key" = "<iam_user_access_key>",
    "aws.glue.secret_key" = "<iam_user_secret_key>",
    "aws.glue.region" = "us-west-2",
    "aws.s3.use_instance_profile" = "false",
    "aws.s3.access_key" = "<iam_user_access_key>",
    "aws.s3.secret_key" = "<iam_user_secret_key>",
    "aws.s3.region" = "us-west-2"
    );

S3-compatible storage system

Use MinIO as an example. Run a command like below:

CREATE EXTERNAL CATALOG deltalake_catalog_hms
PROPERTIES
(
"type" = "deltalake",
"hive.metastore.type" = "hive",
"hive.metastore.uris" = "thrift://xx.xx.xx.xx:9083",
"aws.s3.enable_ssl" = "true",
"aws.s3.enable_path_style_access" = "true",
"aws.s3.endpoint" = "<s3_endpoint>",
"aws.s3.access_key" = "<iam_user_access_key>",
"aws.s3.secret_key" = "<iam_user_secret_key>"
);

Microsoft Azure Storage

Azure Blob Storage
  • If you choose the Shared Key authentication method, run a command like below:

    CREATE EXTERNAL CATALOG deltalake_catalog_hms
    PROPERTIES
    (
    "type" = "deltalake",
    "hive.metastore.type" = "hive",
    "hive.metastore.uris" = "thrift://xx.xx.xx.xx:9083",
    "azure.blob.storage_account" = "<blob_storage_account_name>",
    "azure.blob.shared_key" = "<blob_storage_account_shared_key>"
    );
  • If you choose the SAS Token authentication method, run a command like below:

    CREATE EXTERNAL CATALOG deltalake_catalog_hms
    PROPERTIES
    (
    "type" = "deltalake",
    "hive.metastore.type" = "hive",
    "hive.metastore.uris" = "thrift://xx.xx.xx.xx:9083",
    "azure.blob.storage_account" = "<blob_storage_account_name>",
    "azure.blob.container" = "<blob_container_name>",
    "azure.blob.sas_token" = "<blob_storage_account_SAS_token>"
    );
Azure Data Lake Storage Gen1
  • If you choose the Managed Service Identity authentication method, run a command like below:

    CREATE EXTERNAL CATALOG deltalake_catalog_hms
    PROPERTIES
    (
    "type" = "deltalake",
    "hive.metastore.type" = "hive",
    "hive.metastore.uris" = "thrift://xx.xx.xx.xx:9083",
    "azure.adls1.use_managed_service_identity" = "true"
    );
  • If you choose the Service Principal authentication method, run a command like below:

    CREATE EXTERNAL CATALOG deltalake_catalog_hms
    PROPERTIES
    (
    "type" = "deltalake",
    "hive.metastore.type" = "hive",
    "hive.metastore.uris" = "thrift://xx.xx.xx.xx:9083",
    "azure.adls1.oauth2_client_id" = "<application_client_id>",
    "azure.adls1.oauth2_credential" = "<application_client_credential>",
    "azure.adls1.oauth2_endpoint" = "<OAuth_2.0_authorization_endpoint_v2>"
    );
Azure Data Lake Storage Gen2
  • If you choose the Managed Identity authentication method, run a command like below:

    CREATE EXTERNAL CATALOG deltalake_catalog_hms
    PROPERTIES
    (
    "type" = "deltalake",
    "hive.metastore.type" = "hive",
    "hive.metastore.uris" = "thrift://xx.xx.xx.xx:9083",
    "azure.adls2.oauth2_use_managed_identity" = "true",
    "azure.adls2.oauth2_tenant_id" = "<service_principal_tenant_id>",
    "azure.adls2.oauth2_client_id" = "<service_client_id>"
    );
  • If you choose the Shared Key authentication method, run a command like below:

    CREATE EXTERNAL CATALOG deltalake_catalog_hms
    PROPERTIES
    (
    "type" = "deltalake",
    "hive.metastore.type" = "hive",
    "hive.metastore.uris" = "thrift://xx.xx.xx.xx:9083",
    "azure.adls2.storage_account" = "<storage_account_name>",
    "azure.adls2.shared_key" = "<shared_key>"
    );
  • If you choose the Service Principal authentication method, run a command like below:

    CREATE EXTERNAL CATALOG deltalake_catalog_hms
    PROPERTIES
    (
    "type" = "deltalake",
    "hive.metastore.type" = "hive",
    "hive.metastore.uris" = "thrift://xx.xx.xx.xx:9083",
    "azure.adls2.oauth2_client_id" = "<service_client_id>",
    "azure.adls2.oauth2_client_secret" = "<service_principal_client_secret>",
    "azure.adls2.oauth2_client_endpoint" = "<service_principal_client_endpoint>"
    );

Google GCS

  • If you choose the VM-based authentication method, run a command like below:

    CREATE EXTERNAL CATALOG deltalake_catalog_hms
    PROPERTIES
    (
    "type" = "deltalake",
    "hive.metastore.type" = "hive",
    "hive.metastore.uris" = "thrift://xx.xx.xx.xx:9083",
    "gcp.gcs.use_compute_engine_service_account" = "true"
    );
  • If you choose the service account-based authentication method, run a command like below:

    CREATE EXTERNAL CATALOG deltalake_catalog_hms
    PROPERTIES
    (
    "type" = "deltalake",
    "hive.metastore.type" = "hive",
    "hive.metastore.uris" = "thrift://xx.xx.xx.xx:9083",
    "gcp.gcs.service_account_email" = "<google_service_account_email>",
    "gcp.gcs.service_account_private_key_id" = "<google_service_private_key_id>",
    "gcp.gcs.service_account_private_key" = "<google_service_private_key>"
    );
  • If you choose the impersonation-based authentication method:

    • If you make a VM instance impersonate a service account, run a command like below:

      CREATE EXTERNAL CATALOG deltalake_catalog_hms
      PROPERTIES
      (
      "type" = "deltalake",
      "hive.metastore.type" = "hive",
      "hive.metastore.uris" = "thrift://xx.xx.xx.xx:9083",
      "gcp.gcs.use_compute_engine_service_account" = "true",
      "gcp.gcs.impersonation_service_account" = "<assumed_google_service_account_email>"
      );
    • If you make a service account impersonate another service account, run a command like below:

      CREATE EXTERNAL CATALOG deltalake_catalog_hms
      PROPERTIES
      (
      "type" = "deltalake",
      "hive.metastore.type" = "hive",
      "hive.metastore.uris" = "thrift://xx.xx.xx.xx:9083",
      "gcp.gcs.service_account_email" = "<google_service_account_email>",
      "gcp.gcs.service_account_private_key_id" = "<meta_google_service_account_email>",
      "gcp.gcs.service_account_private_key" = "<meta_google_service_account_email>",
      "gcp.gcs.impersonation_service_account" = "<data_google_service_account_email>"
      );

View Delta Lake catalogs

You can use SHOW CATALOGS to query all catalogs in the current StarRocks cluster:

SHOW CATALOGS;

You can also use SHOW CREATE CATALOG to query the creation statement of an external catalog. The following example queries the creation statement of a Delta Lake catalog named deltalake_catalog_glue:

SHOW CREATE CATALOG deltalake_catalog_glue;

Switch to a Delta Lake Catalog and a database in it

You can use one of the following methods to switch to a Delta Lake catalog and a database in it:

  • Use SET CATALOG to specify a Delta Lake catalog in the current session, and then use USE to specify an active database:

    -- Switch to a specified catalog in the current session:
    SET CATALOG <catalog_name>
    -- Specify the active database in the current session:
    USE <db_name>
  • Directly use USE to switch to a Delta Lake catalog and a database in it:

    USE <catalog_name>.<db_name>

Drop a Delta Lake catalog

You can use DROP CATALOG to drop an external catalog.

The following example drops a Delta Lake catalog named deltalake_catalog_glue:

DROP Catalog deltalake_catalog_glue;

View the schema of a Delta Lake table

You can use one of the following syntaxes to view the schema of a Delta Lake table:

  • View schema

    DESC[RIBE] <catalog_name>.<database_name>.<table_name>
  • View schema and location from the CREATE statement

    SHOW CREATE TABLE <catalog_name>.<database_name>.<table_name>

Query a Delta Lake table

  1. Use SHOW DATABASES to view the databases in your Delta Lake cluster:

    SHOW DATABASES FROM <catalog_name>
  2. Switch to a Delta Lake Catalog and a database in it.

  3. Use SELECT to query the destination table in the specified database:

    SELECT count(*) FROM <table_name> LIMIT 10

Load data from Delta Lake

Suppose you have an OLAP table named olap_tbl, you can transform and load data like below:

INSERT INTO default_catalog.olap_db.olap_tbl SELECT * FROM deltalake_table

Manually or automatically update metadata cache

Manual update

By default, StarRocks caches the metadata of Delta Lake and automatically updates the metadata in asynchronous mode to deliver better performance. Additionally, after some schema changes or table updates are made on a Delta Lake table, you can also use REFRESH EXTERNAL TABLE to manually update its metadata, thereby ensuring that StarRocks can obtain up-to-date metadata at its earliest opportunity and generate appropriate execution plans:

REFRESH EXTERNAL TABLE <table_name> [PARTITION ('partition_name', ...)]

Automatic incremental update

Unlike the automatic asynchronous update policy, the automatic incremental update policy enables the FEs in your StarRocks cluster to read events, such as adding columns, removing partitions, and updating data, from your Hive metastore. StarRocks can automatically update the metadata cached in the FEs based on these events. This means you do not need to manually update the metadata of your Delta Lake tables.

To enable automatic incremental update, follow these steps:

Step 1: Configure event listener for your Hive metastore

Both Hive metastore v2.x and v3.x support configuring an event listener. This step uses the event listener configuration used for Hive metastore v3.1.2 as an example. Add the following configuration items to the $HiveMetastore/conf/hive-site.xml file, and then restart your Hive metastore:

<property>
<name>hive.metastore.event.db.notification.api.auth</name>
<value>false</value>
</property>
<property>
<name>hive.metastore.notifications.add.thrift.objects</name>
<value>true</value>
</property>
<property>
<name>hive.metastore.alter.notifications.basic</name>
<value>false</value>
</property>
<property>
<name>hive.metastore.dml.events</name>
<value>true</value>
</property>
<property>
<name>hive.metastore.transactional.event.listeners</name>
<value>org.apache.hive.hcatalog.listener.DbNotificationListener</value>
</property>
<property>
<name>hive.metastore.event.db.listener.timetolive</name>
<value>172800s</value>
</property>
<property>
<name>hive.metastore.server.max.message.size</name>
<value>858993459</value>
</property>

You can search for event id in the FE log file to check whether the event listener is successfully configured. If the configuration fails, event id values are 0.

Step 2: Enable automatic incremental update on StarRocks

You can enable automatic incremental update for a single Delta Lake catalog or for all Delta Lake catalogs in your StarRocks cluster.

  • To enable automatic incremental update for a single Delta Lake catalog, set the enable_hms_events_incremental_sync parameter to true in PROPERTIES like below when you create the Delta Lake catalog:

    CREATE EXTERNAL CATALOG <catalog_name>
    [COMMENT <comment>]
    PROPERTIES
    (
    "type" = "deltalake",
    "hive.metastore.uris" = "thrift://102.168.xx.xx:9083",
    ....
    "enable_hms_events_incremental_sync" = "true"
    );
  • To enable automatic incremental update for all Delta Lake catalogs, add "enable_hms_events_incremental_sync" = "true" to the $FE_HOME/conf/fe.conf file of each FE, and then restart each FE to make the parameter setting take effect.

You can also tune the following parameters in the $FE_HOME/conf/fe.conf file of each FE based on your business requirements, and then restart each FE to make the parameter settings take effect.

ParameterDescription
hms_events_polling_interval_msThe time interval at which StarRocks reads events from your Hive metastore. Default value: 5000. Unit: milliseconds.
hms_events_batch_size_per_rpcThe maximum number of events that StarRocks can read at a time. Default value: 500.
enable_hms_parallel_process_evensSpecifies whether StarRocks processes events in parallel as it reads the events. Valid values: true and false. Default value: true. The value true enables parallelism, and the value false disables parallelism.
hms_process_events_parallel_numThe maximum number of events that StarRocks can process in parallel. Default value: 4.

Appendix: Understand metadata automatic asynchronous update

Automatic asynchronous update is the default policy that StarRocks uses to update the metadata in Delta Lake catalogs.

By default (namely, when the enable_metastore_cache and enable_remote_file_cache parameters are both set to true), if a query hits a partition of a Delta Lake table, StarRocks automatically caches the metadata of the partition and the metadata of the underlying data files of the partition. The cached metadata is updated by using the lazy update policy.

For example, there is a Delta Lake table named table2, which has four partitions: p1, p2, p3, and p4. A query hits p1, and StarRocks caches the metadata of p1 and the metadata of the underlying data files of p1. Assume that the default time intervals to update and discard the cached metadata are as follows:

  • The time interval (specified by the metastore_cache_refresh_interval_sec parameter) to asynchronously update the cached metadata of p1 is 2 hours.
  • The time interval (specified by the remote_file_cache_refresh_interval_sec parameter) to asynchronously update the cached metadata of the underlying data files of p1 is 60 seconds.
  • The time interval (specified by the metastore_cache_ttl_sec parameter) to automatically discard the cached metadata of p1 is 24 hours.
  • The time interval (specified by the remote_file_cache_ttl_sec parameter) to automatically discard the cached metadata of the underlying data files of p1 is 36 hours.

The following figure shows the time intervals on a timeline for easier understanding.

Timeline for updating and discarding cached metadata

Then StarRocks updates or discards the metadata in compliance with the following rules:

  • If another query hits p1 again and the current time from the last update is less than 60 seconds, StarRocks does not update the cached metadata of p1 or the cached metadata of the underlying data files of p1.
  • If another query hits p1 again and the current time from the last update is more than 60 seconds, StarRocks updates the cached metadata of the underlying data files of p1.
  • If another query hits p1 again and the current time from the last update is more than 2 hours, StarRocks updates the cached metadata of p1.
  • If p1 has not been accessed within 24 hours from the last update, StarRocks discards the cached metadata of p1. The metadata will be cached at the next query.
  • If p1 has not been accessed within 36 hours from the last update, StarRocks discards the cached metadata of the underlying data files of p1. The metadata will be cached at the next query.