You're going to have to read the manual on the different types of indexes. Without knowing what kind of index (Hash, B-tree) you're using and on what kind of table, I cannot help you.
Parts of Chapter 14 of the MySQL manual are good, as is the section on query indexing (starting p.301) of the DuBois book (3rd Edition). -Sheeri On 11/22/05, Mike OK <[EMAIL PROTECTED]> wrote: > I understand that MySQL returns the # of rows changed. What I am wondering > is if I change only one value, therefore a row change, but leave the rest, > what happens. Does the row get removed from the index and re-placed?? Does > MySQL look at each column value first to compare?? Mike > > ----- Original Message ----- > From: "sheeri kritzer" <[EMAIL PROTECTED]> > To: "MySQL List" <mysql@lists.mysql.com> > Sent: November 22, 2005 9:31 AM > Subject: Re: UPDATE and INDEX updates > > > Mike, > > The documentation at > http://dev.mysql.com/doc/refman/5.0/en/update.html explains that MySQL > is aware of the fact that it only needs to update different values -- > for instance, it returns only the # of rows changed, not the # of rows > looked at. Given that, I will extrapolate that MySQL is not going to > re-work an index unless it actually changes a value. > > -Sheeri > > On 11/21/05, Mike OK <[EMAIL PROTECTED]> wrote: > > Hi > > > > I was wondering how the index process worked internally for UPDATE > statements. If I was to "set" a value for a column with the UPDATE > statement but the value was the same, would MySQL re-work the index?? I can > check for data change for each column inside of my code before UPDATE but > want to make sure I need to before going ahead. Mike > > > > -- > MySQL General Mailing List > For list archives: http://lists.mysql.com/mysql > To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED] > > > > -- > No virus found in this incoming message. > Checked by AVG Free Edition. > Version: 7.1.362 / Virus Database: 267.13.5/177 - Release Date: 2005-11-21 > > > -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
