This topic describes the limits that apply to Hologres.

Limits on data query in MaxCompute tables

  • Hologres can scan a maximum of 50 partitions from a partitioned table during a single query.
  • The maximum amount of underlying data scanned for each query is 200 GB, regardless of the number of tables and fields.

Limits on UDFs

  • Hologres does not support user-defined functions (UDFs) that are created in MaxCompute.
  • Hologres does not allow you to create or use PostgreSQL UDFs. However, you can use the built-in functions of PostgreSQL.
  • Hologres does not support the built-in functions of MaxCompute.

Limits on the number of connections

The maximum number of a single Hologres instance depends on the specification of the instance. Execute the following statement for details:
show max_connections;

Limits on data types

The data types of Hologres and PostgreSQL are compatible. However, the data types of Hologres are a subset of the data types of PostgreSQL. For more information, see Data types.

Limits on the purchase of Hologres instances

  • Each Alibaba Cloud account can buy a maximum of three instances per day.
  • Hologres supports the pay-as-you-go and subscription billing methods. You can only change the billing method from pay-as-you-go to subscription. You cannot change the billing method from subscription to pay-as-you-go.
  • If you stop the instance that uses the pay-as-you-go billing method in the Hologres console, you are still charged for the storage resources of the instance.
  • If you are using the subscription billing method and the quota of the storage resources is reached, the billing method is changed to pay-as-you-go.