Re: Does the number of extents affect the performance?

>But hasn't Mohamed demonstrated the pathological worst case ? Is this
>typical ?
>
>We still want to answer the original question of "As far as performance
>goes, do extents matter ?". And the answer seems to be "It -almost-
>never is an issue." Shouldn't we ?
>

In most cases they don't. Like anything, there are pathological cases. To me, going through all the trouble of religiously de-fragging every night just to make sure the worst case doesn't happen is the equivalent of changing the oil on your car every time it rains: we all know water can enter the oil and stuff up the engine, but do you change the oil as soon as it finishes raining? Or do you just check the dipstick?

Same here: why go through all the trouble when there are ways of checking if fragmentation is a problem? If it is, fix it. And correct the allocation so that it doesn't happen again at least on that object. If it is not, then why bother? There are much better ways of using your knowledge and time as a DBA than to do repetitive drone work every night just because on a blue moon and if the wind is blowing from the NNE, the performance might drop.

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-- 
Nuno Souto
nsouto_at_FOSPAMacay.com.au