Deadlocks can occur even with a _single_ server and no clustering,
unless you are running with transaction isolation level set to
"serializable", which comes with a massive performance penalty (it will
give you write concurrency of 1, i.e. as bad as MyISAM).
On 14/02/16 12:36, Matt . wrote:
That is not what I state. If 2 rows are inserted on two different DB
server and one needs to be updated because of these two inserts, this
might run into a lock on the update of this one for each insert.
2016-02-13 21:09 GMT+01:00 Andrea Brancatelli <abrancate...@schema31.it>:
If a two messages arrive at the same time on two different sql server they
are written in two different rows. There's no racing condition.
---
Andrea Brancatelli
Schema31 S.p.a.
Responsabile IT
ROMA - BO - FI - PA
ITALY
Tel: +39. 06.98.358.472
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Il 2016-02-13 19:29 Matt . ha scritto:
Hi,
Thanks, yes I'm checking out the various software I use.
The issue might be that updated status rows are locked, for an example
when 2 messages are stores @ the same time on 2 different sql servers
and need to update another reference row as well.
I see this on logging software happening too for an example.
2016-02-13 19:11 GMT+01:00 Andrea Brancatelli <abrancate...@schema31.it>:
InnoDB/MySQL locking is row level, not table level.
It's highly improbable you'll have any problem like that.
---
Andrea Brancatelli
Schema31 S.p.a.
Responsabile IT
ROMA - BO - FI - PA
ITALY
Tel: +39. 06.98.358.472
Cell: +39 331.2488468
Fax: +39. 055.71.880.466
Società del Gruppo SC31 ITALIA
Il 2016-02-13 17:26 Matt . ha scritto:
Hi,
I'm reviewing how software is acting on loadbalaced MySQL cluster in a
MultiMaster replication.
I see some software having issues to a frontend that is balanced on
weight so if you put a lot of data to the frontend of the cluster, all
nodes are written and if the software locks the table when it writes
to it and the software connects again but the loadbalancer says, ok,
use another server now because the other one is "too busy" you might
run into trouble.
My question is in this case, does DBmail lock the tables when it
writes to it ? otherwise I can sismple change weigth to prio,
otherwise I will let this be as I don't have these issues (yet) with
DBmail.
Thanks!
Matt
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