Basic Concepts¶
Tenant¶
DLI allows multiple organizations, departments, or applications to share resources. A logical entity, also called a tenant, is provided to use diverse resources and services. A mode involving different tenants is called multi-tenant mode. A tenant corresponds to a company. Multiple sub-users can be created under a tenant and are assigned different permissions.
Project¶
A project is a collection of resources accessible to services. In a region, an account can create multiple projects and assign different permissions to different projects. Resources used for different projects are isolated from one another. A project can either be a department or a project team.
Database¶
A database is a warehouse where data is organized, stored, and managed based on the data structure. DLI management permissions are granted on a per database basis.
In DLI, tables and databases are metadata containers that define underlying data. The metadata in the table shows the location of the data and specifies the data structure, such as the column name, data type, and table name. A database is a collection of tables.
Metadata¶
Metadata is used to define data types. It describes information about the data, including the source, size, format, and other data features. In database fields, metadata interprets data content in the data warehouse.
Storage Resource¶
Storage resources in DLI are used to store data of databases and DLI tables. To import data to DLI, storage resources must be prepared. The storage resources reflect the volume of data you are allowed to store in DLI.
SQL Job¶
SQL job refers to the SQL statement executed in the SQL job editor. It serves as the execution entity used for performing operations, such as importing and exporting data, in the SQL job editor.
Spark Job¶
Spark jobs are those submitted by users through visualized interfaces and RESTful APIs. Full-stack Spark jobs are allowed, such as Spark Core, DataSet, MLlib, and GraphX jobs.
OBS Table, DLI Table, and CloudTable Table¶
The table type indicates the storage location of data.
OBS table indicates that data is stored in the OBS bucket.
DLI table indicates that data is stored in the internal table of DLI.
CloudTable table indicates that data is stored in CloudTable.
You can create a table on DLI and associate the table with other services to achieve querying data from multiple data sources.
Constants and Variables¶
The differences between constants and variables are as follows:
During the running of a program, the value of a constant cannot be changed.
Variables are readable and writable, whereas constants are read-only. A variable is a memory address that contains a segment of data that can be changed during program running. For example, in int a = 123, a is an integer variable.