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From: Konstantin Osipov <kostja.osipov@gmail.com>
To: sergepetrenko <sergepetrenko@tarantool.org>
Cc: kirichenkoga@gmail.com, tarantool-patches@dev.tarantool.org,
	v.shpilevoy@tarantool.org
Subject: Re: [Tarantool-patches] [PATCH v4 4/4] replication: do not relay rows coming from a remote instance back to it
Date: Wed, 26 Feb 2020 13:23:19 +0300	[thread overview]
Message-ID: <20200226102319.GB15433@atlas> (raw)
In-Reply-To: <d35a224112e2d32014cf973dc662cc890eca0323.1582709303.git.sergepetrenko@tarantool.org>

* sergepetrenko <sergepetrenko@tarantool.org> [20/02/26 13:00]:
> From: Serge Petrenko <sergepetrenko@tarantool.org>
> 
> We have a mechanism for restoring rows originating from an instance that
> suffered a sudden power loss: remote masters resend the isntance's rows
> received before a certain point in time, defined by remote master vclock
> at the moment of subscribe.
> However, this is useful only on initial replication configuraiton, when
> an instance has just recovered, so that it can receive what it has
> relayed but haven't synced to disk.
> In other cases, when an instance is operating normally and master-master
> replication is configured, the mechanism described above may lead to
> instance re-applying instance's own rows, coming from a master it has just
> subscribed to.
> To fix the problem do not relay rows coming from a remote instance, if
> the instance has already recovered.
> 

A comment like this also belongs to the code. Usually the patch 
that fixes a bug comes along with a test case for a bug, are you
sure you can't submit one?

>  	vclock_copy(&vclock, &replicaset.vclock);
> +	unsigned int id_mask = box_is_orphan() ? 0 : 1 << instance_id;

box_is_orphan() fits the bill, so it's good enough.

I would explain, however, that what we are really looking for
here is whether or not the local WAL accepts writes. As soon as we
started allowing writes to the local WAL, we don't want to get
these writes from elsewhere. 

-- 
Konstantin Osipov, Moscow, Russia

  reply	other threads:[~2020-02-26 10:23 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-26 10:00 [Tarantool-patches] [PATCH v4 0/4] replication: fix applying of rows originating from local instance sergepetrenko
2020-02-26 10:00 ` [Tarantool-patches] [PATCH v4 1/4] box: expose box_is_orphan method sergepetrenko
2020-02-26 10:00 ` [Tarantool-patches] [PATCH v4 2/4] wal: warn when trying to write a record with a broken lsn sergepetrenko
2020-02-26 10:00 ` [Tarantool-patches] [PATCH v4 3/4] replication: implement an instance id filter for relay sergepetrenko
2020-02-26 10:18   ` Konstantin Osipov
2020-02-26 11:16     ` Serge Petrenko
2020-02-26 23:54   ` Vladislav Shpilevoy
2020-02-27  6:48     ` Konstantin Osipov
2020-02-27 13:15     ` Serge Petrenko
2020-02-27 23:33       ` Vladislav Shpilevoy
2020-02-26 10:00 ` [Tarantool-patches] [PATCH v4 4/4] replication: do not relay rows coming from a remote instance back to it sergepetrenko
2020-02-26 10:23   ` Konstantin Osipov [this message]
2020-02-26 11:21     ` Serge Petrenko
2020-02-26 11:58       ` Konstantin Osipov
2020-02-26 15:58         ` Serge Petrenko
2020-02-26 16:40           ` Konstantin Osipov
2020-02-26 23:54   ` Vladislav Shpilevoy
2020-02-27  6:52     ` Konstantin Osipov
2020-02-27 14:13     ` Serge Petrenko
2020-02-27 21:17       ` Serge Petrenko
2020-02-27 23:22         ` Vladislav Shpilevoy
2020-02-28  8:03           ` Serge Petrenko
2020-02-26 23:54 ` [Tarantool-patches] [PATCH v4 0/4] replication: fix applying of rows originating from local instance Vladislav Shpilevoy
2020-02-27 21:24   ` Serge Petrenko
2020-02-27 23:24     ` Vladislav Shpilevoy

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