maria-discuss team mailing list archive

[Roberto Spadim <roberto@xxxxxxxxxxxxx>]

Last time i had a innodb problem i changed all innodb to one file per table

2018-06-06 9:11 GMT-03:00 <Rhys.Campbell@xxxxxxxxxxxx>:

> "why keep using MyISAM as default engine for system tables, when MariaDB
> has Aria or InnoDB ?"
>
> Probably because of the time required to implement and test this. To be
> honest you were probably just very unlucky. Generally the MySQL db receives
> few writes so the chances of corruption are very small. I can honestly say
> I've never had this issue in over 10 years of working with MySQL/MariaDB.
>
> As I recall the documentation does warn you not to change the mysql table
> to another other engine. Has anyone else tried?
>
> Rhys
>
> -----Original Message-----
> From: Maria-discuss [mailto:maria-discuss-bounces+rhys.campbell=
> swisscom.com@xxxxxxxxxxxxxxxxxxx] On Behalf Of Julien Muchembled
> Sent: 06 June 2018 12:38
> To: Maria Discuss <maria-discuss@xxxxxxxxxxxxxxxxxxx>
> Cc: Robin Sébastien <seb@xxxxxxxxxx>
> Subject: [Maria-discuss] Why MyISAM as default engine for system tables ?
>
> Hello,
>
> A few weeks ago, we got the following fatal error when starting mariadb:
>
> [Note] Starting crash recovery...
> [Note] Crash recovery finished.
> [ERROR] mysqld: Table './mysql/db' is marked as crashed and should be
> repaired
> [Warning] Checking table:   './mysql/db'
> [ERROR] mysql.db: 1 client is using or hasn't closed the table properly
> tch value count at row 1 [ERROR] Aborting
>
> Unfortunately, what led to this is unclear. We only rebooted the machine.
> Maybe a hw raid issue. We did a copy at that time. I tried recently if it
> could be repaired but I don't have the a fatal error anymore. We also don't
> know why system tables were touched during the reboot.
>
> Anyway, given the description of Aria ("Crash-safe tables with MyISAM
> heritage"), I understand that MyISAM is not crash-safe. Then, why keep
> using MyISAM as default engine for system tables, when MariaDB has Aria or
> InnoDB ?
>
> Not sure a crash-safe engine would have helped in the above case (there's
> no miracle for data corruption). But we'd like at least that all our
> mariadb setups are crash-safe (e.g. power cuts) and we use InnoDB partly
> for that. And I don't know if a InnoDB DB could be always recoverable if
> the 'mysql' DB is lost but we don't want to do manually (and learn how to)
> what the machine can do automatically.
>
> Julien
>
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-- 
Roberto Spadim
SPAEmpresarial - Software ERP
Eng. Automação e Controle