When I installed my wiki for the first time a couple of years ago, MyISAM was chosen as
the default option so I went with that. I was looking up the history of this list for
comments on InnoDB vs MyISAM. I've seen people, including Brion (below), recommending
InnoDB. Rob Church also had the same opinion:
http://wikimedia.7.n6.nabble.com/MYISAM-or-InnoDB-best-for-Mediawiki-td6917…
However for example on the following article, some disadvantages of InnoDB are talked
about:
http://www.mysqlperformanceblog.com/2009/01/12/should-you-move-from-myisam-…
So it seems like both of them have advantages and disadvantages and so I'm really
confused about what to do - whether to stay where I am, or convert to InnoDB. So my first
questions are:
- I keep regular backups and haven't had DB problems in the past. Should I really move
to InnoDB? If I had to convert the DB, I can always do it in the future without any
problems, correct?
- Will I have any problems later if I stay on MyISAM?
I have MW 1.16.15 and am going to upgrade to 1.18.0. I have Shell access. Now the DB has
mixed tables (Semantic MW did its setup using InnoDB). Its about 1GB in size. The wiki
isnt too big, but say the DB size could go to a few GBs in a few years.
Suppose I decided to move to InnoDB. My next questions were:
- Whats the procedure for this conversion? I will be working on a copy of the database.
- I'm assuming there will be no long term issues about website speed and reliability
or anything else.
thanks
Eric
________________________________
From: Brion Vibber <brion(a)pobox.com>
To: MediaWiki announcements and site admin list <mediawiki-l(a)Wikimedia.org>
Sent: Tuesday, December 5, 2006 8:48 PM
Subject: Re: [Mediawiki-l] Mysql ISAM vs InnoDB
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Jim Hu wrote:
$wgDBtransactions gets set to true if using InnoDB
tables. Is there
an advantage to using InnoDB tables?
The disadvantage is that with MySQL there is a file, ibdata1, that
seems to grow endlessly if InnoDB tables are used. See
http://bugs.mysql.com/bug.php?id=1341
We're wondering if we should just convert everything to MyISAM. Any
thoughts?
MyISAM tables are subject to a much higher likelihood of data
corruption, and cannot be read consistently (eg for backups) without
locking the database.
You may notice that the majority of complaints about corrupt tables
involving MediaWiki are about the 'searchindex' table, which is created
as MyISAM due to the requirements of the fulltext index.
In most wiki situations your database will indeed only grow, so the
table space not reclaiming disk space on deletions is usually not a
problem. In the wiki, all editing history is retained, and the space
from the rare small records that are actually removed will simply be
taken up by further edits.
If you for some reason want to import a lot of data, then delete it all,
then never work with any database data ever again, well... that's pretty
weird. ;) But as suggested in your link you can use per-table InnoDB
spaces in recent versions of MySQL, or you can use the more fragile
MyISAM tables, or you can "defragment" the table space by dumping it
out, deleting the space, and reimporting it.
In some situations MyISAM tables may also be faster, which could be
useful for certain kinds of statistical or other use.
- -- brion vibber (brion @
pobox.com)
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