I'm using New Relic to monitor one of my sites, and about every two weeks my Apdex drops through the floor. This appears to be down to SQL Azure.
What I know:
- Requests Per Minute are the same as they are every working day at that particular time. There isn't a spike at all compared to the same time yesterday or last week.
- Performance goes from about 100ms on average to 12 seconds on average.
- No code changes have happened in the week prior.
- Restarting the Azure Web Site that accesses this database makes no difference.
- Scaling upwards on the front end Web Site makes no difference.
- There don't appear to be any unclosed connections or undisposed connection objects.
Interestingly, what does seem to work to resolve it instantly is to change the scale of the database - in ANY direction. Moving it from S0 to S1 fixes it; moving it from S2 to S1 fixes it. Obviously, it's not possible to "restart" an Azure database, but this process seems to do something.
I'm unsure how to investigate this further. Does anybody have any suggestions or thoughts?