Skip to main content

MySQL: Disk Usage Can Never Shrink When Using InnoDB

One of the startups I work for is a recommendation engine. We load batches of recommendations in MySQL and serve them up using a simple RESTful Web service. Each batch of recommendations can be quite large--often multiple gigs. We delete batches and even drop databases all the time.

However, we just hit a brick wall. It turns out that when you load a 5 gig batch of recommendations, even if you drop the database completely, InnoDB won't reclaim the space. Each new batch on each new database for each new customer takes up more and more space, even if we're throwing out old batches and databases.

This issue is covered here. It's been around since 2003, and it's marked "Not a Bug". Our staging server just went down because we ran out of disk space. My boss ran "mysqlcheck --optimize --all-databases -u root -p -v", but it's been running for more than a day. It looks like the only viable alternative is to completely dump every single database on the server, delete the InnoDB data file completely, restart the server, and reload every database from scratch.

Comments

sagara said…
There's an innodb option to have a per-table tablespace (http://dev.mysql.com/doc/refman/5.1/en/multiple-tablespaces.html), which be useful in your case, since dropping the tables involved will free up the diskspace.
jjinux said…
Thanks :)

Popular posts from this blog

Drawing Sierpinski's Triangle in Minecraft Using Python

In his keynote at PyCon, Eben Upton, the Executive Director of the Rasberry Pi Foundation, mentioned that not only has Minecraft been ported to the Rasberry Pi, but you can even control it with Python. Since four of my kids are avid Minecraft fans, I figured this might be a good time to teach them to program using Python. So I started yesterday with the goal of programming something cool for Minecraft and then showing it off at the San Francisco Python Meetup in the evening.

The first problem that I faced was that I didn't have a Rasberry Pi. You can't hack Minecraft by just installing the Minecraft client. Speaking of which, I didn't have the Minecraft client installed either ;) My kids always play it on their Nexus 7s. I found an open source Minecraft server called Bukkit that "provides the means to extend the popular Minecraft multiplayer server." Then I found a plugin called RaspberryJuice that implements a subset of the Minecraft Pi modding API for Bukkit s…

Apple: iPad and Emacs

Someone asked my boss's buddy Art Medlar if he was going to buy an iPad. He said, "I figure as soon as it runs Emacs, that will be the sign to buy." I think he was just trying to be funny, but his statement is actually fairly profound.

It's well known that submitting iPhone and iPad applications for sale on Apple's store is a huge pain--even if they're free and open source. Apple is acting as a gatekeeper for what is and isn't allowed on your device. I heard that Apple would never allow a scripting language to be installed on your iPad because it would allow end users to run code that they hadn't verified. (I don't have a reference for this, but if you do, please post it below.) Emacs is mostly written in Emacs Lisp. Per Apple's policy, I don't think it'll ever be possible to run Emacs on the iPad.

Emacs was written by Richard Stallman, and it practically defines the Free Software movement (in a manner of speaking at least). Stal…

ERNOS: Erlang Networked Operating System

I've been reading Dreaming in Code lately, and I really like it. If you're not a dreamer, you may safely skip the rest of this post ;)

In Chapter 10, "Engineers and Artists", Alan Kay, John Backus, and Jaron Lanier really got me thinking. I've also been thinking a lot about Minix 3, Erlang, and the original Lisp machine. The ideas are beginning to synthesize into something cohesive--more than just the sum of their parts.

Now, I'm sure that many of these ideas have already been envisioned within Tunes.org, LLVM, Microsoft's Singularity project, or in some other place that I haven't managed to discover or fully read, but I'm going to blog them anyway.

Rather than wax philosophical, let me just dump out some ideas:Start with Minix 3. It's a new microkernel, and it's meant for real use, unlike the original Minix. "This new OS is extremely small, with the part that runs in kernel mode under 4000 lines of executable code." I bet it&…