Sunday, February 23, 2014

What is COST ?

It is the actual resource consumption, or the estimate of resource consumption.




Translated, this says the following:
The cost is the time spent on single-block reads, plus the time spent on multiblock reads,
plus the CPU time required, all divided by the time it takes to do a single-block read.
Which means the cost is the total predicted execution time for the statement, expressed
in units of the single-block read time.


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