even if I select all columns every time no matter it is Table A or B, A has better 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 > -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql
