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
>>
>
