This topic describes the limits of Hologres.
Limits on data queries in MaxCompute tables
Hologres can scan up to 512 partitions from a partitioned table during a single query.
The maximum amount of underlying data that can be scanned for each query is 200 GB, regardless of the number of tables and fields.
Hologres does not support the built-in functions of MaxCompute.
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 UDFs. However, you can use the built-in functions of PostgreSQL.
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
You can buy up to three instances per day within an Alibaba Cloud account.
Hologres supports the subscription and pay-as-you-go billing methods. You can change the billing method only from pay-as-you-go to subscription. You cannot change the billing method from subscription to pay-as-you-go.
If you stop a pay-as-you-go instance in the Hologres console, you are not charged for computing resources but you are charged for the storage resources of the instance. If you delete the instance, you are no longer charged by Hologres.
If you use the subscription billing method and the quota of storage resources is reached, the billing method is changed to pay-as-you-go for the extra storage resources that you use.