Create a Delta Lake catalog in a StarRocks cluster to query data - E-MapReduce

Use a Delta Lake catalog—an external catalog type in E-MapReduce (EMR) StarRocks—to run SQL queries against Delta Lake data without moving or copying the data. This topic explains how to create a Delta Lake catalog and query Delta Lake tables from an EMR StarRocks cluster.

Prerequisites

Before you begin, ensure that you have:

A cluster with the Delta Lake service, such as a DataLake cluster or a custom cluster. For more information, see Create a cluster
A StarRocks cluster. For more information, see Create a StarRocks cluster

Create a Delta Lake catalog

Syntax

CREATE EXTERNAL CATALOG <catalog_name>
PROPERTIES
(
  "key"="value",
  ...
);

Parameters

catalog_name

Required. The name of the Delta Lake catalog. The name must meet the following requirements:

Can contain letters, digits, and underscores (_), and must start with a letter
Must be 1 to 64 characters in length

PROPERTIES

Required. The properties of the Delta Lake catalog. The required properties vary based on the metadata service used by the Delta Lake data source.

Hive Metastore

Property	Required	Description
`type`	Yes	The type of the data source. Set the value to `deltalake`.
`hive.metastore.uris`	Yes	The URI of the Hive metastore. Format: `thrift://<metastore_IP>:<port>`. The default port is 9083.

Data Lake Formation (DLF)

For more information, see Access external tables whose metadata is stored in DLF.

Example

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

Query data in a Delta Lake table

You can execute the following statement to query data in a specific table of a database:

SELECT * FROM <catalog_name>.<database_name>.<table_name>;

E-MapReduce:Delta Lake data source