Hi Simon,
Simon Funnell wrote:
In the case of hardware failure, no database on this planet can 'guarantee'
there will be no corruption, if you have a single point of failure, and it
fails, everything fails, hence the term single as opposed to many points of
failure.
Of course, it's not reasonable to expect a database to guarantee data
integrity if the hard drive fails, or if the filesystem itself is
susceptible to corruption (like FAT, ext2).
However, MyISAM tables can corrupt if the mysql process is merely killed
during a write, or the power is cut off. Any decent
logging/journaling[1] persistence strategy will protect you from
these--there's no reason in the year 2005 for this to be a point of
failure at all. InnoDB for example should not suffer from this problem,
if it does then the MySQL folks *really* have no clue what they are doing.
[1] If you're not familiar with the mechanics of journaling, see Chapter
7 of:
http://www.nobius.org/~dbg/practical-file-system-design.pdf
One of the most important things about software design, in any area, is the
concept of maximisation and minimisation.
For example, in this case you can only minimise the chance of corruption, or
maximise the chance the of recovery, or both.
My understanding is that InnoDB is (far) less likely than MyISAM to
corrupt and easier to recover if it does. So a vote for MyISAM is
really a vote for speed at the expense of safety. My question is
whether MyISAM is a reasonable default for an enterprise mail server--or
any mail server at all.
Obviously, having both sides of the story present will reveal a fuller
picture, its called the art of abstraction.
If anyone asks you if you glass is half empty or half full, tell them you
design software so your glass is never empty and always filling.
Whoa, now you lost me... :)
Simon
----- Original Message -----
From: "Joe Cheng" <[EMAIL PROTECTED]>
To: "James Developers List" <server-dev@james.apache.org>
Sent: Tuesday, June 28, 2005 12:27 AM
Subject: Re: Innodb better?
http://dev.mysql.com/doc/mysql/en/corrupted-myisam-tables.html
According to this link, killing mysqld or turning off the computer in
mid-write could result in table corruption with MyISAM. Not too
surprising considering it doesn't support transactions. I personally
would find this completely unacceptable for an "enterprise" e-mail server.
Doesn't this terrify everyone else, and if not, why not??
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