A few weeks ago and in MySQL 5.7, I had an ALTER TABLE that failed with a duplicate entry error.  This is old news as it is happening since MySQL 5.6, but I only saw this recently because I am normally using online schema change from the Percona Toolkit (pt-osc) or GitHub's online schema migration (gh-ost).  I do not like that and I am disappointed this has not been improved, so this

In my previous post (Puzzled by MySQL Replication), I describe a weird, but completely documented, behavior of replication that had me scratching my head for hours because it was causing data corruption.  I did not give too many details then as I also wanted allowing you to scratch your head if you wished.  In this post, I describe this behavior in more details.

But first I need to

My MySQL bugs is a list I recently created and intend to keep up to date with issues I have seen.

Since the time that I’ve been using MySQL I have filed quite a few bug reports. Some of these have been fixed and many of the bug reports are actually new feature requests. While working with MySQL Enterprise Monitor I’ve probably filed more feature requests than bug reports.

That’s fine of course and my opinion of what is needed in MySQL or Merlin is one thing,  yours or the MySQL developers is something else. We all have our own needs and find things missing which would solve our specific problems.

If I have ten feature requests open and only one could be added to the software I’d also like to be able to say: this feature is the most important one for me.

However, it seems to me that there is no easy way in the mysql bug tracker at the moment to group together different types of new feature requests into groups of related features and then see the different types of …

This problem is "documented" in two bugs:
http://bugs.mysql.com/bug.php?id=36073
http://bugs.mysql.com/bug.php?id=20001

Why in the world is this just a "documentation fix"? There have been a number of occasions when I've tried to write generic stored procedures that might want to analyze information about temporary tables. For instance, given a SELECT statement, I want to determine what datatypes each select clause produces. A fairly straightforward way to do this might be to run a "create temporary table xyz as (SELECT ... LIMIT 0), to produce an empty temporary table to analyze. This doesn't work however, because there isn't any information on xyz in the information schema! Worse, SHOW statements don't work as a PREPARED STATEMENT so there isn't any way to determine this information in …