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From: Vladislav Shpilevoy via Tarantool-patches <tarantool-patches@dev.tarantool.org>
To: Oleg Babin <olegrok@tarantool.org>,
	tarantool-patches@dev.tarantool.org,
	yaroslav.dynnikov@tarantool.org
Subject: Re: [Tarantool-patches] [PATCH vshard 5/6] router: introduce automatic master discovery
Date: Tue, 6 Jul 2021 23:19:43 +0200
Message-ID: <5156b7dd-13e6-7457-491d-4d66f42eb615@tarantool.org> (raw)
In-Reply-To: <7aa15d86-2ec9-c517-5553-e37f7370f49b@tarantool.org>

>>> And we even don't have exposed replicaset_wait_connected/replicaset_wait_master
>>>
>>> to call it before master will be known. As result several seconds we will get failed requests.
>> I didn't expose them yet because I am very reluctant towards exposing
>> anything until there is an explicit request from a user. Don't want to
>> overload the API.
>>
>>> Also I saw TODO in test that "RO requests should be able to go to replicas" and I expect questions
>>>
>>> about RTO 0 on read requests from our customers.
>> What do you mean as "RTO 0 on read requests"?
>>
> We faced it when developed CRUD module. To perform requests we need to know space schema.
> 
> But all remote schema changes are visible only after request that triggers schema refetch.
> 
> And we had working cluster but the first portion of requests failed because of outdated schema.
> 
> 
> Will we have something similar when we doesn't discover master yet but have replicas and our
> 
> read requests will fail? If it's so please file at least an issue to fix it.

Yes, I understand now. Right, you might have failures, I am afraid. Depending on
your timeout. If there is no master, your request will try to wait for a master's
appearance during the given timeout. It won't fail immediately.

But sometimes it does not even need to wait - it can simply go to a working replica
right away if there is one. I mentioned it in XXX comments in the patch. I created
a ticket: https://github.com/tarantool/vshard/issues/288.

  reply	other threads:[~2021-07-06 21:19 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-01 22:09 [Tarantool-patches] [PATCH vshard 0/6] Master discovery Vladislav Shpilevoy via Tarantool-patches
2021-07-01 22:09 ` [Tarantool-patches] [PATCH vshard 1/6] replicaset: introduce netbox_wait_connected() Vladislav Shpilevoy via Tarantool-patches
2021-07-02 11:46   ` Oleg Babin via Tarantool-patches
2021-07-01 22:09 ` [Tarantool-patches] [PATCH vshard 2/6] test: sort some table prints Vladislav Shpilevoy via Tarantool-patches
2021-07-02 11:46   ` Oleg Babin via Tarantool-patches
2021-07-01 22:09 ` [Tarantool-patches] [PATCH vshard 3/6] storage: introduce vshard.storage._call('info') Vladislav Shpilevoy via Tarantool-patches
2021-07-02 11:46   ` Oleg Babin via Tarantool-patches
2021-07-01 22:09 ` [Tarantool-patches] [PATCH vshard 4/6] config: introduce master 'auto' replicaset option Vladislav Shpilevoy via Tarantool-patches
2021-07-02 11:47   ` Oleg Babin via Tarantool-patches
2021-07-02 21:32     ` Vladislav Shpilevoy via Tarantool-patches
2021-07-05  9:23       ` Oleg Babin via Tarantool-patches
2021-07-01 22:09 ` [Tarantool-patches] [PATCH vshard 5/6] router: introduce automatic master discovery Vladislav Shpilevoy via Tarantool-patches
2021-07-02 11:48   ` Oleg Babin via Tarantool-patches
2021-07-02 21:35     ` Vladislav Shpilevoy via Tarantool-patches
2021-07-05  9:24       ` Oleg Babin via Tarantool-patches
2021-07-05 20:53         ` Vladislav Shpilevoy via Tarantool-patches
2021-07-06  8:54           ` Oleg Babin via Tarantool-patches
2021-07-06 21:19             ` Vladislav Shpilevoy via Tarantool-patches [this message]
2021-07-01 22:09 ` [Tarantool-patches] [PATCH vshard 6/6] router: update master using a hint from storage Vladislav Shpilevoy via Tarantool-patches
2021-07-02 11:49   ` Oleg Babin via Tarantool-patches
2021-07-02 21:36     ` Vladislav Shpilevoy via Tarantool-patches
2021-07-05  9:24       ` Oleg Babin via Tarantool-patches
2021-07-05 20:53         ` Vladislav Shpilevoy via Tarantool-patches
2021-07-06  8:55           ` Oleg Babin via Tarantool-patches
2021-07-02 21:36 ` [Tarantool-patches] [PATCH vshard 7/6] util: truncate too long fiber name Vladislav Shpilevoy via Tarantool-patches
2021-07-05  9:23   ` Oleg Babin via Tarantool-patches
2021-08-03 21:55 ` [Tarantool-patches] [PATCH vshard 0/6] Master discovery Vladislav Shpilevoy via Tarantool-patches

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