| From: | Etsuro Fujita <fujita(dot)etsuro(at)lab(dot)ntt(dot)co(dot)jp> |
|---|---|
| To: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com> |
| Cc: | Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>, Albe Laurenz <laurenz(dot)albe(at)wien(dot)gv(dot)at>, Robert Haas <robertmhaas(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Bruce Momjian <bruce(at)momjian(dot)us>, Josh Berkus <josh(at)agliodbs(dot)com>, Mason S <masonlists(at)gmail(dot)com>, Oleg Bartunov <obartunov(at)gmail(dot)com>, Simon Riggs <simon(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Horizontal scalability/sharding |
| Date: | 2015-09-02 12:55:04 |
| Message-ID: | 55E6F1A8.7010202@lab.ntt.co.jp |
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| Lists: | pgsql-hackers |
On 2015/09/02 20:42, Amit Kapila wrote:
> On Wed, Sep 2, 2015 at 4:19 PM, Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com
> <mailto:pavan(dot)deolasee(at)gmail(dot)com>> wrote:
> > On Wed, Sep 2, 2015 at 3:55 PM, Amit Langote
> <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp <mailto:Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>>
> wrote:
> >> On 2015-09-02 PM 06:41, Amit Langote wrote:
> >> Which, I now realize, is not the worry Amit Kapila's expresses.
> >> The deadlock was *indeed detected* in this case, with all the locks
> in the
> >> same PG instance. In a sharded environment with multiple PG instances,
> >> that becomes tricky. DLM (distributed lock manager/deadlock detector)
> >> seems indeed necessary as Amit K. suspects.
Ah, you are right.
> > Right. XC/XL did not address this issue and they rely on statement
> timeouts to break distributed deadlocks.
> I think that will be difficult for application to decide and then it
> needs to decide the same for all statements which is tricky because
> different statements could take different time. I think it is better to
> have solution for this problem and deadlock should be detected.
+1
Best regards,
Etsuro Fujita
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