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 >> > -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql
