Re: Research/Implementation of Nested Loop Join optimization

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От Tom Lane
Тема Re: Research/Implementation of Nested Loop Join optimization
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Msg-id 8815.1217050707@sss.pgh.pa.us
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Ответ на Re: Research/Implementation of Nested Loop Join optimization  (Ron Mayer <rm_pg@cheapcomplexdevices.com>)
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Ron Mayer <rm_pg@cheapcomplexdevices.com> writes:
> Tom Lane wrote:
>> A backwards scan will get no such overlapping and thus be up to 2X
>> slower, unless the kernel is smart enough to do read-ahead for
>> descending-order read requests.  Which seems not too probable. 

> Linux's old adaptive readahead patches claimed to[1]:

I didn't say that there were *no* platforms that could do it.
        regards, tom lane

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