November 27, 2014

MySQL 5.6’s new replication features: Benefits, Limitations and Challenges

On Wednesday I’ll be leading a webinar exploring MySQL 5.6’s new replication features. And yes, as usual I’ll deliver news on the good, the bad and the ugly (that is to say the benefits, limitations and challenges). The webinar, appropriately titled, “New Replication Features in MySQL 5.6: Benefits, Limitations, and Challenges“, is scheduled for Oct. […]

Replication in MySQL 5.6: GTIDs benefits and limitations – Part 2

The main benefit of using GTIDs is to have much easier failover than with file-based replication. We will see how to change the replication topology when using GTID-based replication. That will show where GTIDs shine and where improvements are expected. This is the second post of a series of articles focused on MySQL 5.6 GTIDs. […]

Replication in MySQL 5.6: GTIDs benefits and limitations – Part 1

Global Transactions Identifiers are one of the new features regarding replication in MySQL 5.6. They open up a lot of opportunities to make the life of DBAs much easier when having to maintain servers under a specific replication topology. However you should keep in mind some limitations of the current implementation. This post is the […]

MySQL 5.6.10 Optimizer Limitations: Index Condition Pushdown

While preparing the webinar I will deliver this Friday, I ran into a quite interesting (although not very impacting) optimizer issue: a “SELECT *” taking half the time to execute than the same “SELECT one_indexed_column” query in MySQL 5.6.10. This turned into a really nice exercise for checking the performance and inner workings of one […]

MySQL Limitations Part 4: One thread per connection

This is the third in a series on what’s seriously limiting MySQL in core use cases (links: part 1, 2, 3). This post is about the way MySQL handles connections, allocating one thread per connection to the server.

MySQL Limitations Part 3: Subqueries

This is the third in a series on what’s seriously limiting MySQL in certain circumstances (links: part 1, 2). This post is about subqueries, which in some cases execute outside-in instead of inside-out as users expect.

MySQL Limitations Part 2: The Binary Log

This is the second in a series on what’s seriously limiting MySQL in certain circumstances (links: part 1). In the first part, I wrote about single-threaded replication. Upstream from the replicas is the primary, which enables replication by writing a so-called “binary log” of events that modify data in the server. The binary log is […]

MySQL Limitations Part 1: Single-Threaded Replication

I recently mentioned a few of the big “non-starter” limitations Postgres has overcome for specific use cases. I decided to write a series of blog posts on MySQL’s unsolved severe limitations. I mean limitations that really hobble it for major, important needs — not in areas where it isn’t used, but in areas where it […]

Figuring out what limits MySQL Replication

Today I was cloning the master using LVM Snapshot and found it was taking quite a while to catch up, which highlighted replication could be the limiting factor for this system quite soon, so I decided to check what is limiting MySQL Replication speed. My first idea was to check it based on slow query […]

MySQL EXPLAIN limits and errors.

Running EXPLAIN for problematic queries is very powerful tool for MySQL Performance optimization. If you’ve been using this tool a lot you probably noticed it is not always provide adequate information. Here is list of things you may wish to watch out. EXPLAIN can be wrong – this does not happen very often but it […]