Re: Ensuring hash tuples are properly maxaligned

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От Thomas Munro
Тема Re: Ensuring hash tuples are properly maxaligned
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Msg-id CAEepm=1oc+hY_Goh8onmLc1q3KjAFDSeZJ7Ea5wzUc30G4jKhA@mail.gmail.com
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Ответ на Re: Ensuring hash tuples are properly maxaligned  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: Ensuring hash tuples are properly maxaligned
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On Wed, Jan 3, 2018 at 2:20 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Andres Freund <andres@anarazel.de> writes:
>> But note that dsa_pointer can be wider than a regular pointer on
>> platforms without atomics support.
>
> Hm.  I did not get that impression from the comments in dsa.h,
> but if it's true then this approach won't work --- and indeed the
> hash code would be actively broken in such a case, so it's a problem
> we must fix.

Maybe Andres is thinking of dsa_pointer_atomic?  dsa_pointer is
normally the size of a pointer (well, really, the size of size_t),
though it could be *narrower* if you don't have atomics or ask for it
with USE_SMALL_DSA_POINTER

-- 
Thomas Munro
http://www.enterprisedb.com


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