List:General Discussion« Previous MessageNext Message »
From:Zheng Li Date:March 9 2012 1:13am
Subject:Re: does the number of column affect performance
View as plain text  
sorry for the duplicate message.
just ignore it.


On 2012/03/09, at 10:11, Zheng Li wrote:

> 
> what if I have to select all columns every time?
> any difference in performance?
> 
> On 2012/02/29, at 4:41, Paul DuBois wrote:
> 
>> 
>> On Feb 28, 2012, at 9:59 AM, Zheng Li wrote:
>> 
>>> for example
>>> there are 2 tables to save same data
>>> table A has 10 columns: a primary key column and 9 blob column
>>> table B has 2 columns : a primary key column and 1 blob column which includes
> all data in 2nd~10th columns of table A
>>> 
>>> are there any differences in performance when selecting, inserting, updating,
> and deleting data.
>> 
>> Sure. For example, with table A, you can select only those blob columns you're
> interested in. With B, you have to select all of them if you want *any* of them.
>> 
>> 
>> -- 
>> Paul DuBois
>> Oracle Corporation / MySQL Documentation Team
>> Madison, Wisconsin, USA
>> www.mysql.com
>> 
> 

Thread
does the number of column affect performanceZheng Li28 Feb
  • Re: does the number of column affect performancePaul DuBois28 Feb
    • Re: does the number of column affect performanceMichael Dykman28 Feb
    • Re: does the number of column affect performanceZheng Li29 Feb
      • Re: does the number of column affect performanceBaron Schwartz29 Feb
        • Re: does the number of column affect performanceJohan De Meersman1 Mar
    • Re: does the number of column affect performanceZheng Li9 Mar
      • Re: does the number of column affect performanceZheng Li9 Mar