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From: Cyrill Gorcunov <gorcunov@gmail.com>
To: Vladislav Shpilevoy <v.shpilevoy@tarantool.org>
Cc: tarantool-patches@dev.tarantool.org
Subject: Re: [Tarantool-patches] [PATCH v2 1/1] memtx: force async snapshot transactions
Date: Mon, 14 Sep 2020 11:12:02 +0300	[thread overview]
Message-ID: <20200914081202.GD269870@grain> (raw)
In-Reply-To: <5a6c33ec7bfffd3d0dd201a1b38cc5205f0f0ea4.1600025872.git.v.shpilevoy@tarantool.org>

On Sun, Sep 13, 2020 at 09:39:26PM +0200, Vladislav Shpilevoy wrote:
> Snapshot rows contain not real LSNs. Instead their LSNs are
> signatures, ordinal numbers. Rows in the snap have LSNs from 1 to
> the number of rows. This is because LSNs are not stored with every
> tuple in the storages, and there is no way to store real LSNs in
> the snapshot.
> 
> These artificial LSNs broke the synchronous replication limbo.
> After snap recovery is done, limbo vclock was broken - it
> contained numbers not related to reality, and affected by rows
> from local spaces.
> 
> Also the recovery could stuck because ACKs in the limbo stopped
> working after a first row - the vclock was set to the final
> signature right away.
> 
> This patch makes all snapshot recovered rows async. Because they
> are confirmed by definition. So now the limbo is not involved into
> the snapshot recovery.
> 
> Closes #5298
Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com>

  reply	other threads:[~2020-09-14  8:12 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-13 19:39 Vladislav Shpilevoy
2020-09-14  8:12 ` Cyrill Gorcunov [this message]
2020-09-14  9:15 ` Serge Petrenko
2020-09-14 20:01 ` Vladislav Shpilevoy

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