Re: Fix for consume_xids advancing XIDs incorrectly

On 2024/10/29 18:00, Yushi Ogiwara wrote:
>>>
>>>
>>>         consumed = XidSkip(nextXid);
>>>         if (consumed > 0)
>>>                 TransamVariables->nextXid.value += (uint64) consumed;
>>>
>>> BTW, the code snippet above in consume_xids_shortcut() could potentially set
>>> the next XID to a value below FirstNormalTransactionId? If yes, we should account for
>>> FirstNormalFullTransactionId when increasing the next XID, similar to
>>> how FullTransactionIdAdvance() handles it.
>>
>> Good catch. I agree with you. We need to do something similar to what
>> FullTransactionIdAdvance() does so that it does not appear as a
>> special 32-bit XID.
>>
>> Regards,
>
> I think this is not the case since XidSkip returns min(UINT32_MAX - 5 - low, *), which prevents the wrap-around of nextXid.

Yes, you're right. Thanks for the correction!

Regards,

--
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION