From: | Petr Jelinek <petr(at)2ndquadrant(dot)com> |
---|---|
To: | Francisco Olarte <folarte(at)peoplecall(dot)com>, 余森彬 <justdoit920823(at)gmail(dot)com> |
Cc: | pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Why PostgreSQL doesn't implement a semi sync replication? |
Date: | 2016-11-11 18:12:29 |
Message-ID: | 238f12fe-8128-0601-5e0b-06a6298baa23@2ndquadrant.com |
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Lists: | pgsql-hackers |
On 11/11/16 16:03, Francisco Olarte wrote:
> On Fri, Nov 11, 2016 at 4:40 AM, 余森彬 <justdoit920823(at)gmail(dot)com> wrote:
>> As we know, the synchronous commit process is blocked while receives
>> from acknowledgement from standby in
>> PostgreSQL.This is good for data consistence in master and standby, and
>> application can get important data from standby.But
>> when the standby crash or network goes wrong, the master could be hang.Is
>> there a feature plan for a semi sync like MySQL
>> InnoDB(set a timer, and become asynchronous when timeout)?
>
> JMO, but it seems this basically means any process should be dessigned
> to cope with the posibility of not having replicated data after
> commit, so, why bother with synchronous replication in the first
> place?
It's often more acceptable to say "we lose data when 2 servers die (or
are in problems)" than "we lose data when 1 server dies" and it's also
more acceptable to say "we stop answering when we lose 2 servers" but
not "we stop answering when we lose 1 server", and semisync replication
works for combination of these two.
--
Petr Jelinek http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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