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From Joe Cheng <c...@joecheng.com>
Subject Re: Innodb better?
Date Tue, 28 Jun 2005 03:45:51 GMT
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" <code@joecheng.com>
>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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>>    
>>
>
>
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>  
>

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