Re: WIP: BRIN multi-range indexes

On 3/26/21 3:45 PM, Tomas Vondra wrote:
> On 3/26/21 3:04 PM, Tomas Vondra wrote:
>> On 3/26/21 2:55 PM, Tom Lane wrote:
>>> Tomas Vondra <tomas.vondra@enterprisedb.com> writes:
>>>> I recall seeing "bus error" on sparc with other patches because of
>>>> alignment issues, so I wonder if this is what's happening here.
>>>
>>> Try compiling with the address sanitizer enabled.  Per c.h,
>>>
>>>  * Testing can be done with "-fsanitize=alignment -fsanitize-trap=alignment"
>>>  * on clang, or "-fsanitize=alignment -fno-sanitize-recover=alignment" on gcc.
>>>
>>
>> Bingo! I see the one failing x86_64 machine has -fsanitize=alignment.
>>
> 
> Yeah, the deserialization is borked. It assumes it can just point into
> the serialized representation of the summary, but that is "compacted" by
> ignoring alignment. Hence the failures. For me it fails only for timetz
> and interval types, but perhaps sparc is more sensitive, or maybe it's
> about 32/64 bits too (the only backtrace I'm aware of is from snapper,
> so assuming it's 32bits it'd make sense it fails on int8).
> 
> I have a feeling I made the same mistake in serialization of MCV stats
> some time ago, shame on me. I'll get this fixed.
> 

I've pushed a fix, ensuring proper alignment. There was a second issue
that'd affect big endian systems, so I fixed that too.


regards

-- 
Tomas Vondra
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