db.m7g.large allows 832 connections. When 1,600 clients connected at once, 916 were refused; through RDS Proxy all 1,600 succeeded, with the slowest waiting 12 seconds. The measurements at 100, 400, 800 and 1,600, the errors you'll see, and what a fresh AWS SDK client per request does under the same burst.
Direct to Postgres
Through RDS Proxy
Connections that succeeded when opened all at once, RDS Postgres 17 on db.m7g.large. Our measurements, November 2026. max_connections was 832.
This is the failure serverless teams hit first: a burst of Lambda invocations or new containers, each opening its own connection. The full report has the latency of every storm, the exact errors Postgres returns, what RDS Proxy costs in wait time, and how many idle connections it takes to slow down everyone else (in our test, none of up to 368).
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Lambda Cold Starts With Postgres, RDS Proxy and DynamoDB, Measured: VPC or Not, 200 at Once
Node.js 22 functions on arm64 took 570–650 ms end to end on a cold start, whether they talked to Postgres directly, through RDS Proxy, or to DynamoDB, and a function in a VPC was no slower than one outside it. Bursts of 200 simultaneous cold starts all succeeded. Warm, RDS Proxy added about 3 ms per query.
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Database Failover Downtime on AWS, Measured: RDS Multi-AZ 13–15 Seconds, Aurora Under 2
We wrote to Postgres every 50 ms and forced failovers. RDS Multi-AZ lost writes for 13.0 and 14.8 seconds; in one trial the switch began three minutes after the reboot was requested. Aurora PostgreSQL lost writes for 2.0 and 0.5 seconds, one failed write each time. The full timelines, the errors your application will see, and what to set so it recovers on its own.
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As of November 9, 2026. Provided as is, for general information, and accurate to the best of our knowledge on the date shown. Not legal, compliance, tax, financial or other professional advice. Prices, limits and vendor services change; check current vendor documentation before relying on anything here. Terms of use.