You can no longer purchase ApsaraMQ for Kafka instances by topic. Instances that were purchased by topic are converted to instances purchased by partition.
You can upgrade or downgrade your instance specifications by partition but not by topic, regardless of whether your instance was purchased by topic or by partition. Instances that were purchased by topic are automatically converted to instances purchased by partition based on the following rules.
- The topics are converted to the corresponding number of partitions. The limit on the number of partitions that are allowed to be purchased is still effective. 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 next integer. For example, you purchased a subscription Standard Edition instance. The instance specification provides 50 topics and a bandwidth of 20 MB/s, and you additionally purchased 10 topics. After the instance is converted, the total number of partitions available to this instance is 1,000 + 10 × 40.602 = 1,407 based on the coefficient provided in the following table. For the numbers of partitions that are included in different specifications, see Billing rules. - After the additionally purchased topics are converted to partitions, if the total number of partitions is less than the number of partitions you use, we supplement the difference for free to ensure your normal usage of the service.
For example, if the number of total partitions after conversion is 1,000, but the number of partitions you use is 1,100, we provide 100 partitions for free.
- 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 lists 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 |