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varchar vs char [message #1559]

Thu, 26 July 2007 04:32

kfeng
Messages: 2
Registered: July 2007

Junior Member

Hi,

I need some performance advice. If I don't care about disk space and I only care about speed, should I be using char instead of varchar?

If it makes a difference, I am using MyISAM. Thanks in advance.

- Ken

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Re: varchar vs char [message #1603 is a reply to message #1559 ]

Thu, 16 August 2007 08:49

Peter
Messages: 405
Registered: August 2006

Senior Member
Super Guru

It makes a difference.

Benchmark to know which one for your particular app:)

Generally CHARs are only good when the columns are short, ie CHAR(20) or if there is close length of the strings stored

VARCHAR(255) storing average length of 10 usually will be faster than CHAR(255)

Peter Zaitsev, MySQL Performance Expert
MySQL Performance Blog - http://www.mysqlperformanceblog.com
MySQL Consulting http://www.mysqlperformanceblog.com/mysql-consulting/

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Re: varchar vs char [message #1656 is a reply to message #1603 ]

Tue, 21 August 2007 03:33

kfeng
Messages: 2
Registered: July 2007

Junior Member

Thanks! You've confirmed the slowdown I felt after switching from varchar() to char(). I will go back to varchar().

Thanks again.

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