Re: select_parallel test failure: gather sometimes losing tuples (maybe during rescans)?

On Tue, Mar 6, 2018 at 5:04 AM, Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
> Thomas Munro wrote:
>> On Sun, Mar 4, 2018 at 10:46 PM, Magnus Hagander <magnus@hagander.net> wrote:
>> > Um. Have you actually seen the "mail archive app" cut long threads off in
>> > other cases? Because it's certainly not supposed to do that...
>>
>> Hi Magnus,
>>
>> I mean the "flat" thread view:
>>
>> https://www.postgresql.org/message-id/flat/CAFjFpRfQ8GrQvzp3jA2wnLqrHmaXna-urjm_UY9BqXj=EaDTSA@mail.gmail.com
>>
>> The final message on that page is not the final message that appears
>> in my mail client for the thread.  I guessed that might have been cut
>> off due to some hard-coded limit, but perhaps there is some other
>> reason (different heuristics for thread following?)
>
> You're thinking of message
> https://www.postgresql.org/message-id/CAFjFpRfa6_n10cn3vXjN9hdTqneH6A1rfnLXy0PnCP63T2putw@mail.gmail.com
> but that is not the same thread -- it doesn't have the References or
> In-Reply-To headers (see "raw"; user/pwd is archives/antispam).  Don't
> know why though -- maybe Gmail trimmed References because it no longer
> fit in the DKIM signature?  Yours had a long one:
> https://www.postgresql.org/message-id/raw/CAEepm%3D0VCrC-WfzZkq3YSvJXf225rDnp1ypjv%2BrjKO5d0%3DXqFg%40mail.gmail.com

Huh.  Interesting.  It seems that Gmail uses a fuzzier heuristics, not
just "In-Reply-To", explaining why I considered that to be the same
thread but our archive didn't:

http://www.sensefulsolutions.com/2010/08/how-does-email-threading-work-in-gmail.html

I wonder why it dropped the In-Reply-To header when Ashutosh replied...

-- 
Thomas Munro
http://www.enterprisedb.com