Optimizations for Derived Tables
Derived tables are subqueries in the FROM clause. Prior to MariaDB 5.3/MySQL 5.6, they were too slow to be usable. In MariaDB 5.3/MySQL 5.6, there are two
optimizations which provide adequate performance:
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Condition Pushdown into Derived Table Optimization
If a query uses a derived table (or a view), the first action that the que... -
Derived Table Merge Optimization
MariaDB 5.3 introduced the derived table merge optimization. -
Derived Table with Key Optimization
Since MariaDB 5.3, the optimizer can create an index and use it for joins with other tables. -
Lateral Derived Optimization
Lateral Derived optimization, also referred to as "Split Grouping Optimization".
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