Re: Cosmic ray hits integerset - Mailing list pgsql-hackers

From Andrey Borodin
Subject Re: Cosmic ray hits integerset
Date
Msg-id 188B9595-FBBB-4283-AB11-1C4DB4B432FF@yandex-team.ru
Whole thread Raw
In response to Re: Cosmic ray hits integerset  (Alvaro Herrera <alvherre@alvh.no-ip.org>)
List pgsql-hackers

> 22 июня 2021 г., в 19:21, Alvaro Herrera <alvherre@alvh.no-ip.org> написал(а):
>
> On 2021-Jun-22, Thomas Munro wrote:
>
>> Hi,
>>
>> Here's a curious one-off failure in test_integerset:
>>
>> +ERROR:  iterate returned wrong value; got 519985430528, expected 485625692160
>
> Cosmic rays indeed.  The base-2 representation of the expected value is
> 111000100010001100011000000000000000000
> and that of the actual value is
> 111100100010001100011000000000000000000
>
> There's a single bit of difference.

I've tried to explain this as not a single-event upset, but integer overflow in 30-bits mode of simple8b somewhere. But
foundnothing so far. Actual error is in bit 35, and next mode is 60-bit mode. 

Looks like cosmic ray to me too.

Best regards, Andrey Borodin.


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