You can no longer purchase ApsaraMQ for Kafka instances by topic specification. Existing instances purchased by topic specification are converted to instances purchased by partition specification.
You can upgrade or downgrade your ApsaraMQ for Kafka instance only based on partition specification, regardless of whether you purchased the instance by topic or partition specification. Instances purchased by topic specification are automatically converted to instances purchased by partition specification based on the following rules:
The topics that you additionally purchased on the existing instance are converted to partitions with the same price. However, the number of partitions after conversion cannot exceed the maximum number of partitions that you can purchase. The total number of partitions after conversion is calculated by using the following formula:
Total number of partitions after conversion = Number of partitions included in the instance specification + Number of topics additionally purchased x Conversion coefficient.
The calculation result is rounded up to the nearest integer. For example, you purchased a subscription Standard Edition instance that includes 60 topics (50 topics in the specification and 10 additionally purchased topics) and provides a bandwidth of 20 MB/s. After the instance is converted, the total number of partitions on the instance is 1,407 based on the coefficient provided in the following table. The partition number is calculated by using the following formula: 1,000 + 10 × 40.602 = 1,407. For information about partition quotas that are included in different specifications, see Billing rules.
If the total number of partitions is less than the number of partitions that you use after the additionally purchased topics are converted to partitions, Alibaba Cloud supplements the difference free of charge to ensure your normal use.
For example, if the number of total partitions after conversion is 1,000, but the number of partitions that you use is 1,100, Alibaba Cloud provides 100 partitions free of charge.
After the conversion, the number of topics and the number of groups are updated based on the number of partitions. The number of topics is equal to the total number of partitions. The number of groups is equal to the total number of partitions multiplied by two.
The following table describes the coefficients for converting the number of additionally purchased topics to the number of partitions.
Billing method | Conversion coefficient |
Subscription | 23.913 |
Pay-as-you-go | 45.045 |