RDS Serveless V1 Timeouts


Since a few hours ago, we have been getting seemingly random timeouts from our RDS Serverless 1 cluster. They are very simple single table queries, eg looking up a user. A query can fail, then succeed as normal when running immediately again. Successful queries don't appear to be any slower than usual.

We have been using serverless since its launch, and have not experienced this before. Queries are called from different EC2 instances, they all exhibit the same problem, so I don't think the problem is there. The servers have been running for months, no recent changes.

The timeouts are similar to what happens when I try to access the database from a different VPC without granting access. Maybe the connections are being routed through a different something??


  • Setting up some tests and I am totally lost. Simple php page on a new server setup:

    $pdo = new PDO("mysql:host=$servername", $username, $password);

    Keep reloading page, connects OK about 4/5 times.

asked 7 months ago42 views
2 Answers

Any chance your usage of the database is less than it used to be, and you're scaling down to 0? Cold starts are pretty long - usually over 30 seconds so do cause timeouts.

answered 7 months ago
  • No, it is set to a minimum level 2 capacity units.

  • For example, we have a button on our dashboard to reload a list of the user documents. Click that 4 times in a row and it will work, then the 5th one will fail. And may then work on the next 2, then timeout again. All running the same code on the same server.


And as quickly as the timeouts started, they stopped about 10 hours after they started. I did start a new database and the servers had no trouble connecting to it, so I was about to do a snapshot / restore to a new serverless database, when the old database started working again. No idea why.

answered 7 months ago

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