This topic provides answers to some frequently asked questions about MaxCompute.

What professional skills are required to use MaxCompute?

MaxCompute supports various data tunnels of computing models to meet your business requirements in different scenarios. To use MaxCompute for data analysis, you need only to be capable of using programming languages, such as SQL, Python, and Java.

Does MaxCompute provide an effective method to monitor business data?

MaxCompute allows you to configure data monitoring rules only by using the Data Quality feature of DataWorks. MaxCompute cannot monitor the changes in the fields of external data sources.

What is the role of a MaxCompute project?

A project is a basic organizational unit of MaxCompute. Similar to a database or schema in a traditional database system, a project is used to isolate users and control access requests. A project contains multiple objects, such as tables, resources, functions, and instances. You can have permissions to manage multiple projects. You can access objects of another project from your project after security authorization.

How do I obtain an AccessKey pair in MaxCompute?

You can go to the AccessKey Pair page to create or query an AccessKey pair.

If the AccessKey pair of the current account is disabled and a new AccessKey pair is created, are the auto triggered nodes that are created by using the previous AccessKey pair affected?

Yes, the auto triggered nodes that are created by using the previous AccessKey pair are affected. If you disable or delete an AccessKey pair, nodes in your DataWorks workspace fail to be run. Proceed with caution.

Does MaxCompute automatically compress data when I create a MaxCompute table? Can I specify the compression format and storage format?

Yes, MaxCompute automatically compresses data at a ratio of 3:1 to 5:1. The default storage format is AliORC and cannot be changed.

Which types of tables are supported by MaxCompute?

Internal tables and external tables are supported by MaxCompute. MaxCompute V2.0 and later support external tables.
  • Data of internal tables is stored in MaxCompute. Data types of columns in internal tables can be any data types that are supported by MaxCompute.
  • Data of external tables is not stored in MaxCompute. The data can be stored in Object Storage Service (OSS) or Tablestore. MaxCompute records only metadata of external tables. You can use external tables of MaxCompute to process unstructured data that is stored in OSS or Tablestore. The unstructured data includes video, audio, genetic, meteorological, or geographic data.

To accomplish tasks by using user-defined functions (UDFs) or MapReduce, what resources do I need to use?

  • UDF: After you write a UDF, you must package it into a JAR file and upload the file to MaxCompute as a resource. When you run the UDF, MaxCompute automatically downloads the JAR file and obtains the code to run the UDF. JAR files are a type of MaxCompute resource. When you upload a JAR file, a resource is created in MaxCompute.
  • MapReduce: After you write a MapReduce program, you must package it into a JAR file and upload the file to MaxCompute as a resource. When you run the MapReduce program, the MapReduce framework automatically downloads the JAR file and obtains the code to run the MapReduce program.

You can upload text files and MaxCompute tables to MaxCompute as different types of resources. Then, you can read or use these resources when you run UDFs or MapReduce programs.

How do I understand common error messages in MaxCompute and troubleshoot issues based on the messages?

Common error messages in MaxCompute are defined in the following standard format: Error code: General description - Context-related description. Common error messages of MaxCompute SQL, MapReduce, and Tunnel jobs are different. For more information about error messages, see Error code overview.