Starburst Hive connector

The Starburst Hive connector is an extended version of the Hive connector with configuration and usage identical.

Additional information:

• Metastores
• Hive connector with Amazon S3
• Hive connector with Azure Storage
• Google Cloud Storage
• Hive connector with IBM Cloud Object Storage
• Hive connector storage caching
• Hive connector security configuration
• Object storage file formats

Requirements

• Fulfill the Hive connector requirements.

• Additional features of the connector require a valid Starburst Enterprise license, unless otherwise noted.

Extensions

The Starburst Hive connector supports improvements detailed in the security and performance sections, and includes following additional extensions:

Amazon Glue support

Statistics collection is supported for Hive Metastore and Amazon Glue.

Ceph support

The connector supports querying data on Ceph storage.

Dell ECS and ObjectScale support

The connector supports querying data on Dell ECS or ObjectScale storage.

Cloudera support

The connector supports the Cloudera Data Platform (CDP).

MinIO support

The connector supports querying data on MinIO storage.

OpenX JSON format support

The connector supports reading and writing data to tables as JSON files, and use the OpenX JSON serialization and deserialization (serde) from the Java class org.openx.data.jsonserde.JsonSerDe.

Existing tables using that serde and all the associated serde properties are handled automatically.

The actual serde implementation is a fork of the original OpenX serde. It is updated to be compatible with the Hive 3 APIs used in SEP. The binary package of the forked serde implementation is available from Starburst Support. You can install the package in your systems reading and writing to your Hive-managed storage with Hive 3 for optimal compatibility.

Configuration

The connector configuration is similar to the configuration for the base Hive connector, with these additional properties:

Starburst Hive connector properties

Property name	Description
hive.azure.abfs.oauth2.passthrough	Set to true to reuse the Azure Active Directory (AD) token for access to the Azure Blob Storage. For more information, see Azure AD credential pass-through.
hive.hdfs.auth-to-local.config-file	Path to configuration file for mapping usage with storage caching
hive.hdfs.auth-to-local.refresh-period	Refresh period for mapping file with storage caching
materialized-views.*	Various properties for materialized view usage and configuration.

SQL support

The connector supports all of the SQL statements listed in the Hive connector documentation.

The following section describes additional SQL operations that are supported by SEP enhancements to the Trino connector.

• Materialized view management, see also Materialized views and Automated materialized view management

• Flush filesystem cache

Procedures

Use the CALL statement to perform data manipulation or administrative tasks. Procedures are available in the system schema of each catalog.

Flush filesystem cache

• system.flush_filesystem_cache()

  Flushes filesystem cache of a specific table. By default, this function accepts a schema name and a table name as parameters. You can flush the filesystem cache for specific partitions. For example, the following system call flushes the filesystem cache of a specific partition of the MY_TABLE table:

  CALL system.flush_filesystem_cache('TPCH_SCHEMA', 'MY_TABLE', ARRAY['col2'], ARRAY['group1']);
  

Materialized views

The connector supports Materialized view management, with the following requirements:

• The cache service must be configured and running

• Catalogs must be configured to allow materialized views.

In the underlying system, each materialized view consists of a view definition and a storage table. The storage table name is stored as a materialized view property. The materialized data is stored in that storage table.

Note

If you are a data engineer or platform administrator, read our cache service introduction for an overview of setting up the cache service and using materialized views.

The CREATE MATERIALIZED VIEW statement specifies the query to define the data for the materialized view, the refresh schedule, and other parameters used by the cache service. The query can access any available catalog and schema. Storage configuration for the materialized view must be supplied with table properties in the WITH statement. The optional automatic refresh is also configured with properties set in the WITH clause.

Note

The format table property is not supported for materialized views created with the Hive connector. These materialized views use the default file format configured in the optional hive.storage-format catalog configuration property, which defaults to ORC.

Once the storage tables are populated, the materialized view is created, and you can access it like a table using the name of the materialized view.

Materialized views are populated with data and refreshed manually with the REFRESH MATERIALIZED VIEW command, or by the Automated materialized view management.

Use the SHOW CREATE MATERIALIZED VIEW statement to view the complete CREATE MATERIALIZED VIEW statement for a materialized view, including the properties in the WITH clause.

Dropping a materialized view with DROP MATERIALIZED VIEW removes the definition and the storage table.

Configuration

To enable materialized views you must:

• Create a storage schema to contain the storage tables for materialized views.

• Specify the required configuration properties in the catalog properties file for each desired catalog to enable materialized view creation and usage in that catalog.

Both are discussed in this section.

The following are the required catalog configuration properties for a deployment that connects to the cache service using HTTPS on the default port:

materialized-views.enabled=true
materialized-views.namespace=<your_namespace>
materialized-views.storage-schema=<your_storage_schema>
cache-service.uri=https://<cache-service-hostname>:8543
cache-service.user=<starburst-user>
cache-service.password=<starburst-password>

The following are the required catalog configuration properties for a deployment that connects to the cache service using an insecure HTTP connection on the default port:

materialized-views.enabled=true
materialized-views.namespace=<your_namespace>
materialized-views.storage-schema=<your_storage_schema>
cache-service.uri=http://<cache-service-hostname>:8180

The following table lists all available catalog configuration properties related to materialized views. Instructions for creating the required storage schema follow this table.

Catalog configuration properties for materialized views

Property name	Description	Required
materialized-views.enabled	Set to true to enable materialized views.	true
materialized-views.storage-catalog	Specifies the catalog that contains the schema used to store the storage tables for the materialized views. Defaults to the catalog used for the materialized view itself.	false
materialized-views.storage-schema	Specifies the schema used to store the storage tables for the materialized views. Ensure that the proper access control exists on that schema to prevent users from directly accessing the storage tables.	true
materialized-views.namespace	Used by the cache service to create a fully-qualified name for the materialized views, and to identify which catalog is used to run the scheduled refresh queries.	true
materialized-views.allow-run-as-invoker	Directs SEP to run as the user submitting the query when present in a catalog and set to true. If not present or set to false, it attempts to run as the view’s owner. Equivalent catalog session property is materialized_views_allow_run_as_invoker. This is required to be set to true for creating materialized views that include WITH (run_as_invoker = true).	false
materialized-views.run-as-invoker-default-value	Specifies default value for the run-as-invoker property.	false
cache-service.uri	The URI of the SEP cache service.	true

The storage schema must be defined in the catalog properties file.

materialized-views.storage-schema=views_cache_storage

If it does not exist yet, you must create it with a defined location:

CREATE SCHEMA example.views_cache_storage WITH (location = 's3a://<s3-bucket-name>/hivepostgres_views/views_cache_storage/');

In addition, the schema for the materialized view itself must exist. If it does not exist, you must create it:

CREATE SCHEMA example.views_schema WITH (location = 's3a://<s3-bucket-name>/hivepostgres_views/views_schemas');

With the cache service running, the catalog configured and the schemas defined, you can proceed to create a materialized view. In this example, a materialized view named example.example_schema.example_materialized_view is created:

CREATE MATERIALIZED VIEW example.example_schema.example_materialized_view
WITH (
  grace_period = '15m',
  max_import_duration = '1m'
) AS
  SELECT *
  FROM example.public.example_table
  WHERE example_field IN ( 'examplevalue1', 'examplevalue2' )
  ;

The query, specified after AS, can be any valid query, including queries accessing one or multiple other catalogs.

The properties for the view are stored in the cache service database, and the data in the storage schema, example.example_mvstorage.

Once the materialized view has been created, you can query the data. If the data is not yet cached, the query runs against the source data instead. You can force the materialized view to cache at any time by running a REFRESH statement:

REFRESH MATERIALIZED VIEW example.example_schema.example_materialized_view;

To query data in the materialized view, use a SELECT statement as you would for any other table:

SELECT * FROM example.example_schema.example_materialized_view;

You can also use the materialized view in more complex queries, just like any other table.

Access to a materialized view is much faster, since the data is readily available in the storage table and no computation is necessary. The data however does use storage in addition to the source data. Use the following query to determine the catalog, schema, and name of the storage table:

SELECT * FROM system.metadata.materialized_views WHERE name = 'viewname';

Then use the hidden properties of the storage table to compute an estimate for the used storage:

SELECT SUM(size) table_size, COUNT(file) num_files
FROM (
  SELECT
    "$path" AS file,
    "$file_size" AS size
  FROM <storage_catalog>.<storage_schema>.<storage_table>
)
GROUP BY file, size;

Troubleshooting

Whether your materialized views are refreshed manually or by the cache service using WITH clause parameters, refreshes may fail if columns are added or renamed at the source. If this happens, drop the materialized view, and create it again.

ALTER MATERIALIZED VIEW SET PROPERTIES

The extended Starburst Hive connector adds support for ALTER MATERIALIED VIEW SET PROPERTIES statements.

ALTER MATERIALIZED VIEW
  exampleMaterializedView
SET PROPERTIES
  cron = '*/15 * * * *',
  refresh_interval = DEFAULT;

When a materialized view property that impacts the storage layout or an incremental refresh property is altered, a new storage table is created. If a materialized view property that does not affect the storage layout is changed, such as refresh_interval or grace_period, the existing storage table continues to be used.

For example, the following ALTER MATERIALIZED VIEW statement changes the storage layout of exampleMaterializedView by altering the partitioned_by property, resulting in a new storage table for the materialized view:

ALTER MATERIALIZED VIEW
  exampleMaterializedView
SET PROPERTIES
  partitioned_by = ARRAY['regionkey'];

Automated materialized view management

The connector uses the cache service to manage metadata and maintenance of materialized views, related storage tables, and other aspects.

When the CREATE MATERIALIZED VIEW statement runs initially, the cache services picks up processing asynchronously after its configured refresh-interval and delay, which defaults to two minutes. The defined query is then run and used to populate the storage tables. The processing time depends on the complexity of the query, the cluster performance, and the performance of the storage.

Configuration properties are specified in the WITH clause when creating a materialized view:

Properties for materialized view refresh automation

Property name	Description	Default
refresh_interval	Minimum duration between refreshes of the materialized view, for example refresh_interval = '1d' for one day. Refresh interval must be greater than or equal to five minutes, and is defined as a duration. The cache service refreshes the materialized view after this interval, on the service’s next refresh as defined by its refresh-interval and delay configuration properties. Cannot be used with cron.
cron	Unix cron expression specifying a schedule for regular refresh of the materialized view, for example 30 2 * * *. The cache service refreshes the materialized view according to this schedule, on the service’s next refresh as defined by its refresh-interval and delay configuration properties. Cannot be used with refresh_interval.
max_import_duration	Maximum allowed execution time for the refresh of the materialized view to complete. Measured from the scheduled time to the completion of the query execution. If a refresh fails for exceeding the maximum duration, the cache service attempts a refresh at the next scheduled time.	30m
grace_period	After a view’s TTL (Time to Live, calculated as refresh_interval + max_import_duration) has expired, the cache service waits the specified grace_period before queries running against it are terminated. If no grace_period is defined, the cache service defaultGracePeriod is used. NOTE: If you use this field, you must specify a value greater than the defaultGracePeriod defined in the cache service. Specifying a value less than the default results in error.	10m
incremental_column	Column used during incremental refresh by the service to apply an incremental_column > max(incremental_column) filter when loading data incrementally from the source table. This facilitates loading only newer data from the source table instead of the entire table in each refresh iteration. If no column is specified, the cache service execute a full refresh. The columns need to be monotonically increasing with each new record. Typically types are dates or increasing integer values used as identifiers.
namespace	Namespace used by the cache service to create a fully qualified name for materialized views in a catalog.
run_as_invoker	Validate access to tables and data referenced by materialized view as invoker. If you want to set this to true, the catalog property materialized-views.allow-run-as-invoker needs to be set to true as well.	false

In the following example, a materialized view named customer_total_return in example.example_schema is created to automatically refresh daily at 2:30AM:

CREATE MATERIALIZED VIEW example.example_schema.customer_total_return
WITH (
  grace_period = '5m',
  max_import_duration = '30m',
  cron = '30 2 * * *'
) AS
    SELECT
      sr_customer_sk ctr_customer_sk,
      sr_store_sk ctr_store_sk,
      sum(sr_return_amt) ctr_total_return
    FROM
    tpcds.sf1.store_returns,
    tpcds.sf1.date_dim
    WHERE ( (sr_returned_date_sk = d_date_sk) AND (d_year = 2000) )
    GROUP BY sr_customer_sk, sr_store_sk
;

After a materialized view is refreshed, at the end of the effective grace period, any new query requests that arrive after the new refresh is complete are run against the new contents. Query requests created before a refresh is complete are run against the previously existing contents until the effective grace period for that table is over.

Troubleshooting

When you first create a materialized view, it is helpful to be able to determine the state of a refresh, particularly when a refresh has failed or the view data appears to be stale. This can happen when the refresh takes longer than the combined max_import_duration and effective grace period. Materialized views have their own metadata tables located in the default schema of the cache service database that contain current state and other information. Metadata tables are named as the materialized view name with $imports added to the end. For example, given a materialized view, example.example_schema.customer_total_return, run the following query to refresh and view the metadata for your materialized view:

SELECT * FROM example.example_schema."customer_total_return$imports"

Note

You must enclose <your_table_name>$imports in quotes so that the query parser handles the dollar sign correctly.

The resulting metadata table contains the following fields:

• status - Scheduled, Running, Finished, Failed, Timeout

• max_import_duration - The value originally set in the CREATE AS statement

• start_time - As computed from the cron or refresh_interval

• finish_time

• row_count

• error

The metadata for a refresh is maintained until the effective grace period passes.

Performance

The connector includes a number of performance improvements, detailed in the following sections.

Dynamic row filtering

Dynamic filtering, and specifically also dynamic row filtering, is enabled by default. Row filtering improves the effectiveness of dynamic filtering for a connector by using dynamic filters to remove unnecessary rows during a table scan. It is especially powerful for selective filters on columns that are not used for partitioning, bucketing, or when the values do not appear in any clustered order naturally.

As a result the amount of data read from storage and transferred across the network is further reduced. You get access to higher query performance and a reduced cost.

You can use the following properties to configure dynamic row filtering:

Dynamic row filtering properties

Property name	Description
dynamic-row-filtering.enabled	Toggle dynamic row filtering. Defaults to true. Catalog session property name is dynamic_row_filtering_enabled.
dynamic-row-filtering.selectivity-threshold	Control the threshold for the fraction of the selected rows from the overall table above which dynamic row filters are not used. Defaults to 0.7. Catalog session property name is dynamic_row_filtering_selectivity_threshold.
dynamic-row-filtering.wait-timeout	Duration to wait for completion of dynamic row filtering. Defaults to 0. The default causes query processing to proceed without waiting for the dynamic row filter, it is collected asynchronously and used as soon as it becomes available. Catalog session property name is dynamic_row_filtering_wait_timeout.

Storage caching

The connector supports the default storage caching. In addition, if HDFS Kerberos authentication is enabled in your catalog properties file with the following setting, caching takes the relevant permissions into account and operates accordingly:

hive.hdfs.authentication.type=KERBEROS

Additional configuration for Kerberos is required.

If HDFS Kerberos authentication is enabled, you can also enable user impersonation using:

hive.hdfs.impersonation.enabled=true

The service user assigned to SEP needs to be able to access data files in underlying storage. Access permissions are checked against impersonated user, yet with caching in place, some read operations happen in context of system user.

Auth-to-local user mapping

The connector supports auth-to-local mapping of the impersonated username during HDFS access. This requires enabling HDFS impersonation and setting the hive.hdfs.auth-to-local.config-file property to a path containing a mapping file in the format described in auth-to-local translations file. You can configure regular refresh of the configuration file with hive.hdfs.auth-to-local.refresh-period.

Starburst Cached Views

The connector supports Starburst Cached Views and can therefore be configured for table scan redirection and materialized views to improve performance.

Security

The connector includes a number of security-related features, detailed in the following sections.

Built-in access control

If you have enabled built-in access control for SEP, you must add the following configuration to all Hive catalogs:

hive.security=starburst

Azure AD credential pass-through

Credential pass-through is available for read operations and INSERT INTO statements with Azure AD. To use Azure Active Directory (AD) with credential pass-through, you must include the following configuration in the config.properties file:

http-server.authentication.oauth2.scopes=https://storage.azure.com/user_impersonation,openid
http-server.authentication.oauth2.additional-audiences=https://storage.azure.com

If you use the Azure AD as the identity provider when you integrate with Azure Storage, you can reuse the AD token to access Azure Storage blobs.

To reuse the AD token, set the following access properties in the catalog properties file:

hive.azure.abfs.oauth2.passthrough=true

Enable the OAuth 2.0 token pass-through authentication type with the following configuration in Config properties:

http-server.authentication.type=DELEGATED-OAUTH2

You must grant the Azure application user_impersonation API permissions for Azure Storage. You can further read about it in the Azure docs

To ensure blobs are accessible, read about Azure Storage access configuration: * Roles for the Azure Storage * Access control model in ADLS Gen2 * Managing ACLs in ADLS Gen2

For more information about DELEGATED-OAUTH2, see OAuth 2.0 token pass-through.

You can only set one type or group of access properties in a catalog properties file. Setting more than one prevents SEP from running properly. The valid access property combinations for the catalog properties file include the following:

• hive.azure.abfs.oauth2.passthrough.

• hive.azure.abfs-storage-account and hive.azure.abfs-access-key.

• hive.azure.abfs.oauth.endpoint, hive.azure.abfs.oauth.client-id, and hive.azure.abfs.oauth.secret.

Authorization options

SEP includes built-in access control for use with the Hive connector that provides global, system-level security.

HDFS permissions

Before running any CREATE TABLE or CREATE TABLE ... AS statements for Hive tables in SEP, you need to check that the operating system user running the SEP server has access to the Hive warehouse directory on HDFS.

The Hive warehouse directory is specified by the configuration variable hive.metastore.warehouse.dir in hive-site.xml, and the default value is /user/hive/warehouse. If that is not the case, either add the following to jvm.config on all of the nodes: -DHADOOP_USER_NAME=USER, where USER is an operating system user that has proper permissions for the Hive warehouse directory, or start the SEP server as a user with similar permissions. The hive user generally works as USER, since Hive is often started with the hive user. If you run into HDFS permissions problems on CREATE TABLE ... AS, remove /tmp/presto-* on HDFS, fix the user as described above, then restart all of the SEP servers.

LDAP user translation

The connector supports LDAP-based user translation with a HMS metastore and/or HDFS object storage system.

When using LDAP-based user translation, you must configure the appropriate prefix for the service you’re connecting to.

For a HMS metastore, the hive.metastore.thrift.impersonation.enabled catalog configuration property must be set to true. For a HDFS object storage system, the hive.hdfs.impersonation.enabled catalog configuration property must be set to true.

Limitations

The following limitation apply in addition to the limitations of the Hive connector.

• Reading ORC ACID tables created with Hive Streaming ingest is not supported.

• Redirections are supported for Hive tables but not Hive views.

Hive 3 related limitations

• For security reasons, sys system catalog is not accessible in SEP.

• Hive’s timestamp with local zone data type is not supported in SEP. It is possible to read from a table having a column of this type, but the column itself will not be accessible. Writing to such a table is not supported.

• SEP does not correctly read timestamp values from Parquet, RCFile with binary serde and Avro file formats created by Hive 3.1 or later due to Hive issues HIVE-21002, HIVE-22167. When reading from these file formats, SEP returns different results.