About MySQL development (Optimizer mainly)

I did more CTE blogging: check it out here and here !

I realize that these last months I have not published anything... it's because I was quite busy developing a prominent feature: [Recursive] Common Table Expressions , also known as [recursive] CTE , [recursive] subquery factoring , WITH [RECURSIVE] clause. This feature is available today, in a Labs release of the MySQL Server. In my post here , you will find more information: syntax, capacities, examples... Feels good to have this big piece of work finally out!

Hello! I have posted this entry on the MySQL Server team's blog: Using the aggregate functions ANY, SOME, EVERY with MySQL   .

Hello! I have posted this entry on the MySQL Server team's blog: Storing UUID Values in MySQL Tables

Hi! Just to say I wrote this new post about only_full_group_by tricks, on the MySQL Server team's blog.

I just posted on the Server team's blog , an account on my recent only_full_group_by work. We have made significant improvements in 5.7.5, worth a look!

[ this is a re-posting of what I published on the  MySQL server team blog a few days ago ]   When the MySQL server receives a SELECT query, the query goes through several consecutive phases: parsing : SQL words are recognized, the query is split into different parts following the SQL grammar rules: a list of selected expressions, a list of tables to read, a WHERE condition, … resolution : the output of the parsing stage contains names of columns and names of tables. Resolution is about making sense out of this. For example, in “ WHERE foo=3 “, “foo” is a column name without a table name; by applying SQL name resolution rules, we discover the table who contains “foo” (it can be complicated if subqueries or outer joins are involved). optimization : finding the best way to read tables: the best order of tables, and for each table, the best way to access it (index lookup, index scan, …). The output is the so-called “plan”. execution : we read tables as dictated ...