Articles

Affichage des articles du 2017

Sudoku Recursive Common Table Expression Solver

Colin, from Percona, wrote a nice post demonstrating a funny use of common table expressions: solving a Sudoku Puzzle . Ok, that's not the type of problem which matters a lot to database users... but it still feels good when he mentions that MySQL's implementation (which I wrote), is the fastest of all three tested DBMSs 😊.

Presentation at PerconaLive in Dublin, 25-27 Sep 2017

Back from the PerconaLive conference! It was nice meeting some old faces 😃 There I presented MySQL's Common Table Expressions; check out my slides , with example queries and some details about the implementation. I got two suggestions from the audience: add to views the same single-materialization which we have in CTEs now (slides 19-27) support outer references in derived tables and CTEs. The first point would speed up queries which reference a view more than once. The second point would make it easier to write certain queries, where a subquery depends on the outer query's current row and this subquery contains a CTE. Will I get to work on any of these? Time will tell...

MySQL 8.0.1: [Recursive] Common Table Expressions in MySQL (CTEs), Part Four – depth-first or breadth-first traversal, transitive closure, cycle avoidance

I published a new CTE blog here .