Sync replication
I have a question regarding synchronus replication.
If i have a master and standby server will sync replication setup..when my
slave dies and master is still active. Will the transaction completes, or
master will wait for slave to commit the transaction and then commits its. ?
Import Notes
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I have a question regarding synchronus replication.
If i have a master and standby server will sync replication setup..when my slave dies and master is still active. Will the transaction completes, or >master will wait for slave to commit the transaction and then commits its. ?
Master will wait for slave to come back up. PG"s replication is not the same as SQLServer/DB2/Oracle
where they allow master to continue operating while the slave is down. useful during scheduled maintenance.
So untill my slave comes up master does not commit any transaction which
means technically my db is non operative?
On Jan 25, 2018 12:23 PM, "Rakesh Kumar" <rakeshkumar464@aol.com> wrote:
Show quoted text
I have a question regarding synchronus replication.
If i have a master and standby server will sync replication setup..whenmy slave dies and master is still active. Will the transaction completes,
or >master will wait for slave to commit the transaction and then commits
its. ?Master will wait for slave to come back up. PG"s replication is not the
same as SQLServer/DB2/Oracle
where they allow master to continue operating while the slave is down.
useful during scheduled maintenance.
correct.
-----Original Message-----
From: Azimuddin Mohammed <azimeiu@gmail.com>
To: Rakesh Kumar <rakeshkumar464@aol.com>
Cc: pgsql-admin <pgsql-admin@postgresql.org>; pgsql-general <pgsql-general@postgresql.org>
Sent: Thu, Jan 25, 2018 8:06 pm
Subject: Re: Sync replication
So untill my slave comes up master does not commit any transaction which means technically my db is non operative?
On Jan 25, 2018 12:23 PM, "Rakesh Kumar" <rakeshkumar464@aol.com> wrote:
I have a question regarding synchronus replication.
If i have a master and standby server will sync replication setup..when my slave dies and master is still active. Will the transaction completes, or >master will wait for slave to commit the transaction and then commits its. ?
Master will wait for slave to come back up. PG"s replication is not the same as SQLServer/DB2/Oracle
where they allow master to continue operating while the slave is down. useful during scheduled maintenance.
Greetings,
On our mailing lists, we prefer that replies be in-line and ask that
users not top-post. Please see my response, in-line, below.
* Azimuddin Mohammed (azimeiu@gmail.com) wrote:
So untill my slave comes up master does not commit any transaction which
means technically my db is non operative?
That's correct, which is why it's encouraged to have multiple replicas
configured when using synchronous replication. In v10, it's possible to
specify how many synchronous replicas are required to have acknowledged
a given transaction before a COMMIT is returned to the applicaiton.
Please review the documentation here:
https://www.postgresql.org/docs/current/static/warm-standby.html#SYNCHRONOUS-REPLICATION
Thanks!
Stephen
On Thu, Jan 25, 2018 at 08:21:43PM -0500, Stephen Frost wrote:
That's correct, which is why it's encouraged to have multiple replicas
configured when using synchronous replication. In v10, it's possible to
specify how many synchronous replicas are required to have acknowledged
a given transaction before a COMMIT is returned to the applicaiton.
Please review the documentation here:https://www.postgresql.org/docs/current/static/warm-standby.html#SYNCHRONOUS-REPLICATION
Be careful about the performance impact if there is network latency
between a primary and its standbys. One small correction to what Stephen
says here. It is possible to define multiple synchronous standbys in
v9.6. v10 has added the possibility to define quorum groups. Note that
the grammar as been kept backward-compatible across versions.
--
Michael
Greetings Michael,
* Michael Paquier (michael.paquier@gmail.com) wrote:
On Thu, Jan 25, 2018 at 08:21:43PM -0500, Stephen Frost wrote:
That's correct, which is why it's encouraged to have multiple replicas
configured when using synchronous replication. In v10, it's possible to
specify how many synchronous replicas are required to have acknowledged
a given transaction before a COMMIT is returned to the applicaiton.
Please review the documentation here:https://www.postgresql.org/docs/current/static/warm-standby.html#SYNCHRONOUS-REPLICATION
Be careful about the performance impact if there is network latency
between a primary and its standbys. One small correction to what Stephen
says here. It is possible to define multiple synchronous standbys in
v9.6. v10 has added the possibility to define quorum groups. Note that
the grammar as been kept backward-compatible across versions.
Ah, yeah, I was thinking of quorum groups when writing that but you're
right that 9.6 added support for multiple synchronous standbys. Older
versions also supported having multiple synchronous standbys configured
but were hard-wired to accept the commit with just one of them
acknowledging it (in a priorty order based on the order of them as
defined in synchronous_standby_names).
Thanks for the clarification!
Stephen