\nLooking back at the three blogs (and hopefully the comments, where others have made some very useful contributions), it’s all quite unsatisfactory, isn’t it? We haven’t solved the problem.
\nAll we’ve proved is that the tests aren’t equivalent, although I think
\nthere’s value in that negative result because I was asked to investigate ‘what is wrong with our environment’.<\/p>\n
One of the problems is that the test runs for between 7 and 12 hours and, viewing a Statspack report covering such long periods, it’s extremely difficult if not impossible to identify what is definitely a problem. However, it wasn’t at all difficult to identify that our environment was experiencing more transaction activity, which unearthed the central flaw in the vendor’s test – they didn’t have most of the standard functionality switched on.<\/p>\n
My usual approach to identifying performance problems with a business task like this is to trace it using event 10046, level 8 or 12 and that would have provided much more detailed information about the task at hand. <\/p>\n
Consider this, though. <\/p>\n
Whilst I’m a fan of session-level tracing, do you think
\nit would have been easier to identify this problem using event 10046 on
\nthe session of interest or not? We would have seen what was holding up
\nthe job by looking at the wait events, but we would have known nothing
\nabout the cause<\/i>, because that was outside of the session we were looking at. We might have seen the batch job waiting for a resource but our deliberately narrow scope wouldn’t include the other jobs running on the system. (We could have switched on tracing at the instance level, particularly as these are test environments, but we would have had a ton of output to review – trust me, I’ve done it!).<\/p>\n
Please don’t take this as a criticism of session-level tracing, but merely a suggestion that there’s room for a variety of performance analysis tools which give different views of a problem. <\/p>\n
I think it’s reasonable to describe the instance-wide scope of Statspack as a weakness. I also think it’s reasonable to describe the instance-wide scope of Statspack as a strength. It depends what you’re trying to achieve. <\/p>\n","protected":false},"excerpt":{"rendered":"