RE: Which plan is better - what COST really means ?
- From: J.Velikanovs@xxxxxxxx
- To: hamcdc@xxxxxxxxxxx
- Date: Sat, 15 Jan 2005 19:00:02 +0200
>I can't speak for JL but basically I think he's basing cost as the
optimizer's
>estimate of IO's to be performed.
Connor,
Which type of IO by your opinion optimizer takes as base type for cost
estimating?
As far as I know different types of operations (FS, IRS, IQS, IFS, FILTER)
execute IO differently. I mean CPU utilization is different for single IO
unit in case of different operations.
Another question is If cost is IO, how optimizer estimates sorting/hash
etc. actions in IO units?
Jurijs
On 2005.01.15 03:01:20 Connor McDonald wrote:
>I can't speak for JL but basically I think he's basing cost as the
optimizer's
>estimate of IO's to be performed.
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