When you change the specifications of a PolarDB-X instance, the billing impact depends on your billing method: pay-as-you-go or subscription.
Pay-as-you-go instances
Pay-as-you-go instances are billed by the hour. After a specification change takes effect, billing switches to the new specifications.
Subscription instances
Changing the specifications of a subscription instance creates a price difference between the original and new specifications for the remaining subscription period. Depending on the direction of change, you either pay the difference or receive a refund.
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Upgrade: Select Upgrade in the console and pay the price difference to apply higher specifications.
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Downgrade: Select Downgrade in the console. The price difference is refunded based on the new specifications.
How the price difference is calculated
The price difference is prorated over the remaining subscription period. All calculations use a standard month of 30 days (720 hours).
Each fee component uses the following formula:
Fee for a specification (remaining period) = Monthly price / 30 / 24 × Remaining days × 24Upgrade — amount to pay
Payment = Fee for new specs (remaining period) − Fee for original specs (remaining period)| Variable | Description |
|---|---|
| Monthly price of new specs | The list price per month for the target specifications |
| Monthly price of original specs | The list price per month for the current specifications |
| Remaining days | Number of days left in the subscription period |
Example: The monthly price of the new configuration is USD 14,400, and the monthly price of the old configuration is USD 7,200. The remaining subscription duration is 50 days. The payment amount is (14,400 / 30 / 24 × 50 × 24) - (7,200 / 30 / 24 × 50 × 24) = USD 12,000.
Payment = (14,400 / 30 / 24 × 50 × 24) − (7,200 / 30 / 24 × 50 × 24)
= 24,000 − 12,000
= CNY 12,000Downgrade — refund amount
Refund = Fee for original specs (remaining period) − Fee for new specs (remaining period)| Variable | Description |
|---|---|
| Fee for original specs (remaining period) | Total fee of the original specifications for the remaining subscription duration |
| Fee for new specs (remaining period) | Total fee of the new specifications for the remaining subscription duration |
Example: A three-month subscription costs USD 3,500 in total. After applying vouchers, you paid USD 3,000. After two months, the remaining value of the original specifications for the last month is USD 1,000. The new specifications cost USD 800 for that remaining month.
Refund = 1,000 − 800 = USD 200Prices
PolarDB-X pricing varies by region, instance type, and storage capacity. For current pricing, visit the PolarDB-X buy page.