Date: Wed, 23 Nov 2016 17:44:56 +0100 From: Miroslav Lachman <000.fbsd@quip.cz> To: =?UTF-8?Q?Morgan_Wesstr=c3=b6m?= <freebsd-database@pp.dyndns.biz>, freebsd-database@freebsd.org Subject: Re: Need some further understanding of MariaDB/MySQL on ZFS Message-ID: <5835C788.6090601@quip.cz> In-Reply-To: <5835B6E9.9000004@pp.dyndns.biz> References: <5834C395.5080305@pp.dyndns.biz> <583554EE.8010304@quip.cz> <5835B6E9.9000004@pp.dyndns.biz>
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Morgan Wesström wrote on 2016/11/23 16:34: > Thank you Miroslav, this was the vital piece of information I needed. It > seems MySQL changed the default value of innodb_file_per_table from 0 to > 1 with version 5.6. > https://dev.mysql.com/doc/refman/5.6/en/server-default-changes.html yes, the default value was changed from Off to On > The parameter isn't mentioned in any of the online ZFS/MySQL wikis or > blogs that I've found, not even FreeBSD's own wiki. I'll take a look on this and prepare some update. > I assume this change > could interfere with people running production systems on ZFS. > Personally I'm reluctant to change default values unless I have a very > good reason to do so, so I will try to find a way to adapt to it. Your > suggestion to put the whole of /var/db/mysql on a 16K recordsize (except > for the logs directory) is probably the way to go. I just need to delve > a little bit further into the subject before I make up my mind. Thank > you again for pointing me in the right direction. innodb_file_per_table = off means that all tables from all databases are in one big file. It has some advantages - faster access, less opened file descriptors... but some disadvantage too - ibdata file can grow but will not shrink if you delete some data from tables / drop tables. It can be a big problem on huge databases with a lot of writes (UPDATE, DELETE, INSERT). We converted few of our DB servers to innodb_file_per_table = On few years ago. innodb_file_per_table = On is better for our type of workload on almost all our machines but your workload can be different and you can benefit from innodb_file_per_table = Off. So you need to test or guess what is better for your setup. Good luck Miroslav Lachman
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