Re: Block level parallel vacuum WIP

On Mon, Oct 23, 2017 at 10:43 AM, Amit Langote
<Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp> wrote:
> On 2017/10/22 5:25, Thomas Munro wrote:
>> On Sun, Oct 22, 2017 at 5:09 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>>> On Tue, Sep 19, 2017 at 3:31 AM, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
>>>>> Down at the bottom of the build log in the regression diffs file you can see:
>>>>>
>>>>> ! ERROR: cache lookup failed for relation 32893
>>>>>
>>>>> https://travis-ci.org/postgresql-cfbot/postgresql/builds/277165907
>>>>
>>>> Thank you for letting me know.
>>>>
>>>> Hmm, it's an interesting failure. I'll investigate it and post the new patch.
>>>
>>> Did you ever find out what the cause of this problem was?
>>
>> I wonder if it might have been the same issue that commit
>> 19de0ab23ccba12567c18640f00b49f01471018d fixed a week or so later.
>
> Hmm, 19de0ab23ccba seems to prevent the "cache lookup failed for relation
> XXX" error in a different code path though (the code path handling manual
> vacuum). Not sure if the commit could have prevented that error being
> emitted by DROP SCHEMA ... CASCADE, which seems to be what produced it in
> this case. Maybe I'm missing something though.
>

Yeah, I was thinking the commit is relevant with this issue but as
Amit mentioned this error is emitted by DROP SCHEMA CASCASE.
I don't find out the cause of this issue yet. With the previous
version patch, autovacuum workers were woking with one parallel worker
but it never drops relations. So it's possible that the error might
not have been relevant with the patch but anywayI'll continue to work
on that.

Regards,

--
Masahiko Sawada
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center