I'm a bit of a newbie to SQL who has been thrown in on the deep end with a server that gets about 2 million queries an hour.
I'm trying to optimise our database and I noticed this in our database runtime information:
Select_full_join 789 The number of joins that do not use indexes. If this value is not 0, you should carefully check the indexes of your tables.
Obviously that is far from optimal. And other red flags are showing too which are probably related to this root problem I believe.
Now, we have a database structure that is not exactly well indexed. We have a unsigned INT as primary key on our tables and then just unindexed columns.
I wonder how I should approach this. Do I need to add indexes to every column? Would that even help? How should I approach this problem?