AWS Aurora自动缩放会导致mysqld_stmt_execute的参数错误

Question

We are running AWS Aurora(Serverless RDS) in our production environment. It has to scale between 2 capacity units(4GB RAM) and 8 capacity units(16GB RAM).

For the last 2 months, our database has never auto-scaled, it was running in the minimum capacity unit. In the past week, due to an increase in system usage, auto-scaling started triggering every few mins. It was scaling between 4 and 8 capacity units during the day time.

And since last week, we were getting an issue(not all the time but every few mins) when our application triggers SQL queries to the database, Incorrect arguments to mysqld_stmt_execute. This error happens for both read & write operations.

So, we suspected auto-scaling might be the reason and we kept the same capacity units for both min(8) and max(8) to avoid scaling. So, scaling didn't happen and we didn't get that error again. So, we confirmed that the error was caused by auto-scaling. Actually, auto-scaling helped us to reduce the cost but unfortunately causes an error.

We don't understand why this error happens during scaling. Can someone explain why scaling causes this issue and how to avoid this?

Or is it something related to connection pooling issue? I've raised it in the connection pooling project as well.

https://github.com/brettwooldridge/HikariCP/issues/1407

Answer 1

这是缓存准备好的语句的问题。当配置新服务器进行扩展并且在新服务器上触发缓存的准备好的语句时，MySQL 会抛出此错误。因此，我们禁用了准备好的语句缓存，并且不再收到错误。

尽管它有效，但我们无法缓存准备好的语句，这可能会稍微影响性能。到目前为止，还好，因为我们没有注意到延迟。