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Message Posted: Wed, 26 Apr 2006 @ 22:04:27 GMT

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Whoa, wait, the "estimated time" is actually an estimated cost, based on all kinds of things, but NOT related to actual CPU time, or wall-clock time or anything. Well, ok, maybe some statistics from a machine that existed at some time in Dayton somewhere.

It's what the optimizer calculates and uses to compare different versions of a plan. So yeah, the confidence level would affect which plan, because the optimizer tries to pick not the best plan, but the least hazardous. But if it ever turned out that the estimated time did actually MATCH the actual time, it still would be affected by the load on the box, 'cause the estimate is for the query running on an empty box.

So use it for what it's designed for, comparing plans!

iv

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