| From: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> |
|---|---|
| To: | Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> |
| Cc: | Nathan Bossart <nathandbossart(at)gmail(dot)com>, Önder Kalacı <onderkalaci(at)gmail(dot)com>, "Hayato Kuroda (Fujitsu)" <kuroda(dot)hayato(at)fujitsu(dot)com>, "shiy(dot)fnst(at)fujitsu(dot)com" <shiy(dot)fnst(at)fujitsu(dot)com>, Peter Smith <smithpb2250(at)gmail(dot)com>, Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com>, "andres(at)anarazel(dot)de" <andres(at)anarazel(dot)de>, "vignesh21(at)gmail(dot)com" <vignesh21(at)gmail(dot)com>, "shveta(dot)malik(at)gmail(dot)com" <shveta(dot)malik(at)gmail(dot)com>, "Takamichi Osumi (Fujitsu)" <osumi(dot)takamichi(at)fujitsu(dot)com>, "dilipbalaut(at)gmail(dot)com" <dilipbalaut(at)gmail(dot)com>, "euler(at)eulerto(dot)com" <euler(at)eulerto(dot)com>, "m(dot)melihmutlu(at)gmail(dot)com" <m(dot)melihmutlu(at)gmail(dot)com>, "marcos(at)f10(dot)com(dot)br" <marcos(at)f10(dot)com(dot)br>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Time delayed LR (WAS Re: logical replication restrictions) |
| Date: | 2023-03-09 05:30:46 |
| Message-ID: | CAA4eK1J_CCa7b6o0hV8O=ApQsiaHn2vcGziC0xYiNkuKqa=Ydw@mail.gmail.com |
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On Wed, Mar 8, 2023 at 9:20 AM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
>
> On Wed, Mar 8, 2023 at 3:30 AM Nathan Bossart <nathandbossart(at)gmail(dot)com> wrote:
> >
>
> > IMO the current set of
> > trade-offs (e.g., unavoidable bloat and WAL buildup) would make this
> > feature virtually unusable for a lot of workloads, so it's probably worth
> > exploring an alternative approach.
>
> It might require more engineering effort for alternative approaches
> such as one I proposed but the feature could become better from the
> user perspective. I also think it would be worth exploring it if we've
> not yet.
>
Fair enough. I think as of now most people think that we should
consider alternative approaches for this feature. The two ideas at a
high level are that the apply worker itself first flushes the decoded
WAL (maybe only when time-delay is configured) or have a separate
walreceiver process as we have for standby. I think we need to analyze
the pros and cons of each of those approaches and see if they would be
useful even for other things on the apply side.
--
With Regards,
Amit Kapila.
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