This is a huge topic. I'd suggest picking up a copy of my book (linked below). You could also start with reading Gail Shaw's articles over here at Simple-Talk[/url].

Yep. Those values in actual execution plans are also estimates. The values for rows, cpu, stuff like that in an actual plan are real values, but the operator costs are...

I'm not sure. I've never run into that particular error and there's very little documentation around it.

That's a very odd error. I did a search on the web and this was the best that I saw.

So I went over to MSDN and found something more useful....

Without a baseline on the old system, you can't possibly see if performance improved.

All you can do now is baseline the new system (baseline means collect a set of performance...

That's a fright all right.

I didn't even read through it all, but at the end I saw this and started laughing

ORDER BY Right([Queue_des_echantillons].[Noechantillon],5)

So much for using an index.

I absolutely recommend going to a file and then importing to the database. It's just cleaner and easier.

However, depending on the counters you're interested in, you can get them from...

endeavour (10/19/2009)

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Thank you for the helpful replies it seems like the concensus is 'it depends'.

Rather than my describing a single theoretical context,

has anyone actualy hired a consultant to advise on...

Yes.

Even if you have talent in-house for tuning performance, you might need to bring in outside help if you're busy or, worst of all, when management doesn't trust that you're...

The cost values displayed in execution plans are estimates. Becaues of this, they won't always add up to 100% or they may add up to WAY over 100%. It's nothing...

Just so you know, this can frequently result in slower backups that cause some visible load on the server. I prefer to backup locally and then move the file across...

There must be an error message reported in the maintenance job or in the logs. Find that error. If it doesn't tell you exactly what the problem is, post it...

Funny, I'm going to come down just the opposite and say that I like option B for the same reasons that Jeff likes option A. I don't like having to...

No accountants here either... Nurses, Receptionists, Sales people... those I've seen try to be DBA's. Nurses weren't so bad, neither were the receptionists... keep the sales people away from the...

It sounds like a classic case of parameter sniffing. Try updating your statistics. If that doesn't resolve the issue, you may need to use an OPTIMIZE FOR hint on the...