In a case that you copy (INSERT INTO .. SELECT ..) a MyISAM table that have a PRIMARY key, it is much faster to insert the new rows in the primary key order: The insertion will be faster: because the primary key cannot disabled, every insertion will also updates the primary key. In a case […]

Query Optimizer is a part of the server that takes a parsed SQL query and produces a query execution plan. MySQL Query Optimizer uses (as one of its parameters) the stored key distribution (Cardinality) mechanism to determine the order in which tables should be joined, when you perform a join on something other than a […]

When I have discovered MySQL User-defined variables at the first time, I didn’t pay much attention to them and didn’t realize their strength. At first, one can think that they are just one of the many unnoticed MySQL features. Well, I was wrong. Here, I will try to summarize their strength, though I think there is […]

There is no question about the MySQL Query Cache greatness.  The MySQL Query Cache feature started his way with some limitations.  However, in time, there were a lot of improvements (fixing) for those limitations. One should test his MySQL version with the Query Cache limitations before using it. Here are some improved limitations I found […]