In the context of CockroachDB Serverless, burst capacity is the monthly reserve of Request Units available to free users to handle bursts of database activity. Paid users will have a larger burst capacity, based on their monthly resource limit. CockroachDB Serverless defines “bursts” as any usage above the 100 RU/second threshold.
Each free user begins the month with a reserve of 10 million Request Units in reserve for bursts, and earns an additional 100 RUs per second (minus whatever amount of RUs are consumed in that second). This burst capacity ensures that even free users can handle sudden usage spikes without decreased database performance. When all available burst capacity has been consumed, the database will return to processing queries at a consumption rate of 100 RUs/second.