Dear Jasper, I may not have been precise in my question, but the Unique Index in question is a two fields index, and I was looking to find out wisdom from the List if there is sense and/or experience in keying second(left) field on in the Unique Index to speed up a search. I am dealing with 32M rows table, where second field in the Unique Index is a date field. Unfortunately for my simple "SELECT MAX(Date) as Latest_Date from THE_TABLE" took 4 minutes and some seconds, so before I will go and buy bigger server I needed to re-assure myself that there is no other way.
I would not bother the List without a good reason and doing what you said before Regards, Mikhail Berman -----Original Message----- From: Jasper Bryant-Greene [mailto:[EMAIL PROTECTED] Sent: Thursday, November 17, 2005 4:19 PM To: Mikhail Berman Cc: mysql@lists.mysql.com Subject: Re: A "key" question Mikhail Berman wrote: > Is it possible or makes sense to key a field that is a part of Unique > Index already? It's possible, but it doesn't make sense. A unique index is a normal index with an added unique constraint. Adding another index on the same field would make no sense (unless the field is a rightmost part of a unique index). Your question would have been answered by checking the archives less than a week back (this question comes up a lot) or reading the manual. Jasper -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
