Databases Reference
In-Depth Information
the system tables to prevent that. And as part of the terms of service, you agree not to
try to get around these limitations.
The MySQL version installed is slightly modified to prevent you from meddling with
the server, but otherwise it seems to be stock MySQL as you know it. We benchmarked
RDS against EBS and EC2 and found nothing beyond the variations we'd expect from
the platform. That is, it looks like Amazon hasn't done any performance enhancements
to the server.
RDS can offer few compelling benefits, depending on your circumstances:
• You can leave the system administration work and even much of the database
administration work to Amazon. For example, they handle replication for you and
ensure you don't mess it up.
• Depending on your cost structure and staffing resources, RDS can be inexpensive
compared to the alternatives.
• The restrictions can be seen as a good thing: Amazon takes away the loaded gun
you might otherwise use to shoot yourself in the foot.
However, it does have some potential drawbacks:
• Because you can't access the server, you can't tell what's going on in the operating
system. For example, you can't measure I/O response time or CPU utilization.
Amazon does provide this through another of its services, CloudWatch. It gives
detailed enough metrics to troubleshoot many performance problems, but some-
times you need the raw data to know exactly what's happening. (You can't use
functions such as
FILE()
to access
/proc/diskstats
, either.)
• You can't get the full slow query log file. You can direct MySQL to log slow queries
to a CSV logging table, but this isn't as good. It consumes a lot more server re-
sources, and it doesn't give high-resolution query response times. This makes it a
bit harder to profile and troubleshoot SQL.
• If you want the latest and greatest, or some performance enhancements such as
those you could get with Percona Server, you're out of luck. RDS doesn't offer
them.
• You must rely on Amazon's support team to resolve some problems that you might
otherwise be able to fix yourself. For example, suppose queries hang, or your server
crashes due to data corruption. You can either wait for Amazon to work on it, or
you can take matters into your own hands. But to do the latter, you have to take
the data elsewhere; you can't access the instance itself to fix it. You have to spend
extra time and pay for additional resources if you want to do this. This isn't just
theoretical; we've gotten lots of support requests for help with things that really
require access to the system to troubleshoot, and aren't really solvable for RDS
users as a result.
