Re: [9.2devel] why it doesn't do index scan only?

On 8 October 2011 19:47, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> wrote:
>>> I did it. It is strange, so your times are significantly slower than I
>>> have. Have you enabled asserts?
>>
>> The table contains 15 million rows with column values randomly
>> selected from the 1-350 range, with 60% within the 1-50 range, and
>> asserts are enabled.
>>
>
> Now I repeated tests on litlle bit wide table with 9 milion rows, but
> without success.
>
> Try to disable asserts. I am not sure, but maybe there significantlly
> change a speed.

Okay, here you go. Results with debug_assertions = false:

Index-only scan: 173.389 ms (78.442 ms)
Index scan: 184239.399 ms (previously 164882.666 ms)
Bitmap scan: 159354.261 ms (previously 154107.415 ms)
Sequential scan: 134552.263 ms (previously 121296.999 ms)

So no particularly significant difference, except with the index-only
scan (which I repeated 3 times and it's about the same each time).

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Thom Brown
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