Optimizing OR Queries in Rails and MySQL


#1

According to MySQL doc, I must use union and temporary tables.

It seems I have to do something along the line of this:

There are cases where I use OR queries quite often. I am talking about
queries like this “where column_1 = 123 OR column_2 = 123”. It seems
MySQL indices cannot properly optimize this.

Are there plugins or snippets out there that automagically hide the
complexity of using temporary tables for such queries?


#2

On May 1, 10:38 am, Moodang removed_email_address@domain.invalid wrote:

According to MySQL doc, I must use union and temporary tables.

It seems I have to do something along the line of this:

http://www.ricroberts.com/articles/2007/09/25/mysql-temporary-tables-

There are cases where I use OR queries quite often. I am talking about
queries like this “where column_1 = 123 OR column_2 = 123”. It seems
MySQL indices cannot properly optimize this.

I don’t think that’s quite true - on mysql5 it should be able to do an
index merge:
http://dev.mysql.com/doc/refman/5.0/en/index-merge-optimization.html

Fred