Could someone cast an eye on the (3 +1s) patch at
http://dev.rubyonrails.org/ticket/10605
?
Thanks,
Fred
On 23 Dec 2007, at 21:49, Trevor Squires wrote:
>
> Hi Fred,
>
> I ran your benchmark and I get similar results. That is, I can't
> duplicate hm:j's findings that going to the raw connection is slower.
>
> So +1 from me, and as James H has done, I've put an alternate patch
> there - use select_value rather than select_all.
>
> Trevor
>
> On 22-Dec-07, at 8:46 AM, Frederick Cheung wrote:
>
>>
>>
>> On 21 Dec 2007, at 18:48, Frederick Cheung wrote:
>>
>>>
>>> On 21 Dec 2007, at 18:18, Josh Susser wrote:
>>>
>>>>
>>>>
>>>> I'm the author of the new exists? code, and I also looked at
>>>> doing it
>>>> with a lower-level connection call instead of a find with :select
>>>> option. I don't have the data around anymore, but as I recall, the
>>>> benchmarks showed that using the select_all approach didn't perform
>>>> as
>>>> well, so I went with the find with :select approach. I hadn't
>>>> thought
>>>> about the after_find callback interaction, and I guess no one else
>>>> has
>>>> run into that problem before now either. Some stuff has changed in
>>>> AR
>>>> that might have affected performance of the select_all approach
>>>> since
>>>> I tried it last, so it might be worth revisiting now.
>>>>
>>>
>>> Well I ended up with that code by taking apart find :first and
>>> removing the instantiation of rows at the end, so I don't think it
>>> should be a problem.
>>> What I posted should be doing exactly what find :first does, but
>>> without the instantiation
>>
>> I ran some numbers today:
>>
>> ids = (1..10000).map { rand 2000000}
>>
>> Benchmark.bmbm do |x|
>> x.report("exists") { ids.each {|id| Question.exists? id} }
>> end
>>
>> Current trunk (find:first)
>>
>> Rehearsal ------------------------------------------
>> exists 4.700000 0.620000 5.320000 ( 6.437581)
>> --------------------------------- total: 5.320000sec
>>
>> user system total real
>> exists 4.690000 0.620000 5.310000 ( 6.574966)
>>
>> select_all
>>
>> Rehearsal ------------------------------------------
>> exists 4.650000 0.740000 5.390000 ( 8.984423)
>> --------------------------------- total: 5.390000sec
>>
>> user system total real
>> exists 4.010000 0.590000 4.600000 ( 5.606526)
>>
>>
>> Not mind blowing and it's obviously not going to make a massive
>> difference to anyone, but for me at least sets aside any performance
>> worries.
>>
>> Fred
>>
>>
>>
>
> >
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