| From: | "Bossart, Nathan" <bossartn(at)amazon(dot)com> |
|---|---|
| To: | "alvherre(at)alvh(dot)no-ip(dot)org" <alvherre(at)alvh(dot)no-ip(dot)org> |
| Cc: | Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com>, "x4mmm(at)yandex-team(dot)ru" <x4mmm(at)yandex-team(dot)ru>, "a(dot)lubennikova(at)postgrespro(dot)ru" <a(dot)lubennikova(at)postgrespro(dot)ru>, "hlinnaka(at)iki(dot)fi" <hlinnaka(at)iki(dot)fi>, "matsumura(dot)ryo(at)fujitsu(dot)com" <matsumura(dot)ryo(at)fujitsu(dot)com>, "masao(dot)fujii(at)gmail(dot)com" <masao(dot)fujii(at)gmail(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: archive status ".ready" files may be created too early |
| Date: | 2021-08-17 18:06:23 |
| Message-ID: | 29C5E5E6-00D1-4B53-9BF7-73E1CB936E41@amazon.com |
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| Lists: | pgsql-hackers |
On 8/17/21, 10:44 AM, "alvherre(at)alvh(dot)no-ip(dot)org" <alvherre(at)alvh(dot)no-ip(dot)org> wrote:
> On 2021-Aug-17, Bossart, Nathan wrote:
>> I've been thinking about the next steps for this one, too. ISTM we'll
>> need to basically assume that the flush pointer jumps along record
>> boundaries except for the cross-segment records. I don't know if that
>> is the safest assumption, but I think the alternative involves
>> recording every record boundary in the map.
>
> I'm not sure I understand your idea correctly. Perhaps another solution
> is to assume that the flush pointer jumps along record boundaries
> *including* for cross-segment records. The problem stems precisely from
> the fact that we set the flush pointer at segment boundaries, even when
> they aren't record boundary.
I think we are in agreement. If we assume that the flush pointer
jumps along record boundaries and segment boundaries, the solution
would be to avoid using the flush pointer when it points to a segment
boundary (given that the segment boundary is not also a record
boundary). Instead, we'd only send up to the start position of the
last record in the segment to standbys.
Nathan
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