Cloudflare’s Hyperdrive MySQL support hits GA after 20 bug fixes

Cloudflare’s Hyperdrive now supports MySQL in general availability, the company announced on October 14, 2026. Hyperdrive, Cloudflare’s database connection pooler for Workers, previously only supported Postgres; MySQL protocol support entered beta last year.

According to Cloudflare, the gap between beta and GA came down to reliability work. “It turns out that the difference between beta and GA is just 20 bug fixes in a trenchcoat,” wrote Pranoy Dutta in the company’s blog post. During the beta, Cloudflare says it tracked how often client connections from a Worker ended in a Hyperdrive-related error and aimed to validate that real-world usage hit its production availability target of 99.99%.

What Hyperdrive does

Hyperdrive is a distributed connection pooler that links Cloudflare Workers to SQL databases. It keeps warm SQL connections open across Cloudflare’s global network and shares them among many Worker requests, and it can cache common queries in the global CDN cache to cut latency and load on the origin database.

Cloudflare notes that opening a SQL connection takes at least five network round trips, which is impractical to repeat per request on a serverless platform. MySQL has an advantage over Postgres here because it doesn’t use a full OS process per connection, though Cloudflare says large deployments can still hit resource limits with many connections.

Emoji and encoding fixes

Two of the beta bugs involved character encoding. One early report was that emojis written to the database came back incorrectly. Hyperdrive negotiates encoding during the startup handshake, and it had been negotiating utf8 — which Cloudflare describes as a deprecated alias for utf8mb3, covering only 1–3 bytes per Unicode code point instead of the full 4 bytes. Switching the handshake to utf8mb4 fixed the emoji problem.

Encoding caused trouble again when Cloudflare added connection cleanup via COM_RESET_CONNECTION, a lightweight command that clears session state so nothing leaks between checkouts. According to Cloudflare, that command resets the connection to the server default rather than the encoding negotiated at startup — so on a server defaulting to latin1, a connection negotiated as utf8mb4 came back as latin1. The fix is to set the encoding to utf8mb4 after every connection reset.

The rare caching bug

Cloudflare says its highest-volume MySQL customer in the beta reported a small but consistent rate of empty query responses where a non-empty response was always expected. The company says it began by reviewing telemetry and the customer’s logic, and describes the resulting investigation as a rare and subtle bug in production. The blog post does not, in the portion available, detail the root cause or the specific fix.

MySQL support in Hyperdrive is now generally available. Developers using Hyperdrive with MySQL can check Cloudflare’s documentation and blog for the full write-up of the debugging process.

Related reading

Sources

• Inside Hyperdrive: How we solved a rare Hyperdrive MySQL caching bug — Cloudflare Blog