Re: BUG #15142: ERROR: MultiXactId nnnnn has not been created yet -- apparent wraparound in v9.5

Query: select * from TABLE_NAME where ctid between '(0,1)'::tid and
'(1,1)'::tid; return ERROR:  MultiXactId 1048586 has not been created
yet -- apparent wraparound

Tuple #161 has ctid = (3220145, 81)

On 04/04/2018 12:22 PM, Tomas Vondra wrote:
> On 04/04/2018 10:20 AM, molofeev wrote:
>> Any ideas?
>>
>>
>> On 04/03/2018 04:36 PM, molofeev wrote:
>>> The last query that working is - select * from TABLE_NAME limit 1
>>> offset 160;
>>>
>>> the next query
>>>
>>> select * from TABLE_NAME limit 1 offset 162;
>>>
>>> return - ERROR: MultiXactId 1048586 has not been created yet --
>>> apparent wraparound
>>> SQL state: XX000
>>>
> Well, as Alvaro mentioned, we need to see the page that contains the
> record with that multixactid. You now know which table it is, and you
> know it's tuple #162. We still don't know which page is it exactly, but
> you can determine that by using CTID:
>
> select * from TABLE_NAME where ctid between '(13,1)'::tid
> and '(14,0)'::tid;
>
> You'll need to start on page 0 and increase it until you get the error
> again. This will scan the whole table, though.
>
> Then you know which page has the broken data, and you can inspect it
> using pageinspect - extract it using raw_page, inspect it using various
> functions in that extension. I don't know how sensitive the data in that
> table is, but perhaps you may share the 8kB page.
>
> FWIW this seems to be some sort of data corruption, where the XID got
> overwritten by a bogus value in some way. The bigger question is how
> many other such cases are there.
>
> regards
>