ljguo_1234 <[EMAIL PROTECTED]> writes:
> I have read the source code
>/cvsroot/pgsql/src/backend/optimizer/path/costsize.c and there is a function
>cost_sort(...). I think the code in 464 to 465 lines must be changed to:
> startup_cost += npageaccesses *
> (1.0 + cost_nonsequential_access(1)) * 0.5;
That would be wrong. Note the definition of cost_nonsequential_access:
* Estimate the cost of accessing one page at random from a relation
* (or sort temp file) of the given size in pages.
regards, tom lane
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