Re: Loadbalanced MySQL Cluster, can deadlock occur ?
Gordan Bobic <[email protected]> Sun, 14 Feb 2016 12:58:12 +0000
| Newsgroups | gmane.mail.imap.dbmail |
|---|---|
| Message-ID | <[email protected]> |
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 <[email protected]>: >> 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 >> Cell: +39 331.2488468 >> Fax: +39. 055.71.880.466 >> Società del Gruppo SC31 ITALIA >> >> >> >> 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 <[email protected]>: >> >> 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 >> _______________________________________________ >> DBmail mailing list >> [email protected] >> http://mailman.fastxs.nl/cgi-bin/mailman/listinfo/dbmail > _______________________________________________ > DBmail mailing list > [email protected] > http://mailman.fastxs.nl/cgi-bin/mailman/listinfo/dbmail > _______________________________________________ DBmail mailing list [email protected] http://mailman.fastxs.nl/cgi-bin/mailman/listinfo/dbmail