There’s a big difference in how plugins are treated in MySQL and how they are treated in Drizzle. The MySQL way has been to create a C API in front of the C++-like (I call it C- as it manages to take the worst of both worlds) internal “API”. The Drizzle way is to have plugins be first class citizens and use exactly the same API as if they were inside the server.

This means that MySQL attempts to maintain API stability. This isn’t something worth trying for. Any plugin that isn’t trivial quickly surpasses what is exposed via the C API and has to work around it, or, it’s a storage engine and instead you have this horrible mash of C and C++. The byproduct of this is that no core server features are being re-implemented as plugins. This means

I had reason to look into the extended secondary index code in MariaDB and MySQL recently, and there was one bit that I really didn’t like.

MariaDB:

share->set_use_ext_keys_flag(legacy_db_type == DB_TYPE_INNODB);

MySQL:

use_extended_sk= (legacy_db_type == DB_TYPE_INNODB);

In case you were wondering what “legacy_db_type” actually does, let me tell you: it’s not legacy at all, it’s kind of key to how the whole “metadata” system in MySQL works. For example, to drop a table, this magic number is used to work out what storage engine to call to drop the table.

Now, these code snippets

The Example storage engine is meant to serve mainly as a code example of the stub of a storage engine for example purposes only (or so the code comment at the start of ha_example.cc reads). In reality however, it’s not very useful. It likely was back in 2004 when it could be used as a starting point for starting some simple new engines (my guess would be that more than a few of the simpler engines started from ha_example.cc).

The sad reality is the complexity of the non-obviousness of the bits o the storage engine API you actually care about are documented in ha_ndbcluster.cc, ha_myisam.cc and ha_innodb.cc. If you’re doing something that isn’t already done by one of those three engines: good luck.

Whenever I looked at ha_example.cc I always wished there was something

I wonder how much longer the ARCHIVE storage engine is going to ship with MySQL…. I think I’m the last person to actually fix a bug in it, and that was, well, a good number of years ago now. It was created to solve a simple problem: write once read hardly ever. Useful for logs and the like. A zlib stream of rows in a file.

You can actually easily beat ARCHIVE for INSERT speed with a non-indexed MyISAM table, and with things like TokuDB around you can probably get pretty close to compression while at the same time having these things known as “indexes”.

ARCHIVE for a long time held this niche though and was widely and quietly used (and likely still is). It has the great benefit of being fairly lightweight – it’s only about 2500 lines of code (1130 if

This is one close to my heart. I’ve recently written on other storage engines: Where are they now: MySQL Storage Engines, The MERGE storage engine: not dead, just resting…. or forgotten and The MEMORY storage engine. Today, it’s the turn of MySQL Cluster.

Like InnoDB, MySQL Cluster started outside of MySQL. Those of you paying attention at home may notice a correlation between storage engines not written exclusively for MySQL and being at all successful.

NDB

Big news at Percona Live MySQL Conference and Expo this week, Tokutek open sourced TokuDB thus making my previous post Where are they now: MySQL Storage Engines out of date in just a few days.

In this case, I really don’t mind. It’s rather exciting that they’ve gone ahead and done this –  and it’s not just a code drop: https://github.com/Tokutek/ft-engine is where things are at, and recent commits were 2hrs and 18hrs ago which means that this is being maintained. This is certainly a good way to grow a developer community.

While being a MySQL engine is really interesting, the MongoDB

I’ve started poking around the MySQL 5.7.1 source tree (although just from tarball as I don’t see a BZR tree yet). I thought I’d share a few thoughts:

• InnoDB temporary tables. Not REDO logged. What does this mean? It’s a huge step in removing the dependency on MEMORY and MyISAM engines for temporary tables used in query execution. With InnoDB temporary tables there is no reason for MEMORY engine to continue to exist, there is absolutely no way in which it is better.
• InnoDB temp tables aren’t insert buffered
  This probably doesn’t really matter as you’re not going to be doing REDO logging for them (plus things are generally short lived)… but it could be a future area for performance improvement
• The

There was once a big hooplah about the MySQL Storage Engine Architecture and how it was easy to just slot in some other method of storage instead of the provided ones. Over the years I’ve repeatedly mentioned how this

While Domas may have rather effictively trolled the discussion with his post on howto configure table/user statistics (which gave me a good chuckle I do have to say), it’s at least incorrect for Percona Server as you have to enable the “userstat” server option :)

That being said, once enabled there are no extra configuration variables to think about. This is a huge advantage over configuring PERFORMANCE_SCHEMA - which has a total of THIRTY configuration options (31 if you include the global enable/disable option).

Some of these thirty odd configuration variables are only going to matter if

A few weekends ago, I started to again look at the code in Drizzle for producing internal temporary tables. Basically, we have a few type of tables:

• Standard
• Temporary (from CREATE TEMPORARY TABLE)
• Temporary (from ALTER TABLE)
• Internal temporary (to help with query execution)

If you’re lucky enough to be creating one of the first three types, you go through an increasingly lovely pile of code that constructs a nice protobuf message about what the table should look like and hands all responsibility over to the storage engine as to how to do that. The basic idea is that Drizzle gets the heck out of the way and lets the storage engine do its thing. This code path looks rather different

Yesterday I wrote about what the diffstat between MySQL 5.5 and MariaDB 5.5 was, and previously to that, about the MariaDB code size as reported by sloccount. Let’s look at MySQL 5.6.

A naive wc based “lines of code” for MySQL 5.6 sql/ directory is ~490kLOC which contasts with MySQL 5.5 being ~375kLOC by the same measure. If we diffstat the sql/ directory like I did for MariaDB 5.5 we get:

 357 files changed, 172871 insertions(+), 67922 deletions(-)

Versus, as you remember from yesterday for MariaDB 5.5 over MySQL 5.5:

 250 files changed, 83639

So, I’ve looked at what sloccount says on the differences between Oracle MySQL over versions of itself and the various MySQL branches around. What I haven’t looked at is the diffstat. Firstly, let’s look at MariaDB.

I’m going to look at MariaDB 5.5.29 as compared to MySQL 5.5.29, both checked out from bzr. A naive diffstat would give us:

 5261 files changed, 1086165 insertions(+), 122751 deletions(-)

And this looks like an awful lot of code that has changed: about 1,086,165 lines! This actually includes a whole other copy of InnoDB in the form of XtraDB. If we take that into account we get:

 5032 files changed, 864997 insertions(+), 125099 deletions(-)

Which is still incredibly

From my previous posts, we have some numbers (excluding NDB) for the size of MySQL, so what about PostgreSQL? Here, I used PostgreSQL git trunk and classing things in the contrib/ directory as plugins. I put the number of lines of code in the src/backend/storage directory down as storage engines LoC but did not count it as non-kernel code.

I’m going to take the numbers from my previous post, MySQL Modularity, Are We There Yet? for the “kernel” size of MySQL – that is, everything that isn’t a plugin or storage engine.

For Linux kernel, I’m just going to use the a-bit-old git tree I have on my laptop. I’ve decided that the following directories are for “plugins” drivers/ arch/ sound/ firmware/ crypto/ usr/ virt/ tools/ scripts/ fs/*/* and everything else is core kernel code.

MySQL is now over four times the size than it was with MySQL 3.23. This has not come in the shape of plugins.

Have we improved modularity over time? I decided to take LoC count for plugins and storage engines (in the case of Drizzle, memory, myisam and innobase are storage engines and everything else comes under plugin). I’ve excluded NDB from these numbers as it is rather massive and is pretty much still a separate thing.

Continuing on from my previous posts, MySQL code size over releases and MariaDB code size I’ve decided to also look into some other code branches. I’ve used the same methodology as my previous few posts: sloccount for C and C++ code only.

There are also other branches around in pretty widespread use (if only within a single company). I grabbed the Google, Facebook and Twitter patches and examined them too, along with Percona Server 5.1 and 5.5.

As the start of a bit of a delve into the various MySQL branches and patch sets that have been around, let’s start looking at the history of MySQL itself. This is how big MySQL has been over all of the major releases since the beginning (where beginning=3.23). (edit: These numbers were all gathered using sloccount and only counting C++ and C source files.)

Taking the inspiration of Valeriy Kravchuk great series of blog posts “Fun with Bugs” (and not http://funwithbugs.com/ which is about both caring for and eating bugs), and since I recently went and run Coverity against Drizzle, I thought I’d have a small series of posts on bugs that it has found (and I’ve fixed).

An idea that has been pervasive in the Drizzle project (and one that I rather subscribe to) is that there is two types of correct: correct and obviously correct. Being obviously correct is much,

Coverity is a static analysis tool, which although proprietary itself does offer a free scanning service for free and open source software (which is great by the way, I totally owe people who make that happen a frosty beverage).

Prompted by someone volunteering to get MariaDB into the Coverity Scan, I realized that I hadn’t actually followed through with this for Drizzle. So, I went and submitted Drizzle. As a quick overview, this is the number of problems of each severity both projects got back:

I don’t know what MySQL may be, but it’d be great to see this out in the open too.

Being clear in licensing is a great benefit to users. I’m quite proud that with Drizzle we got to a really simple situation:

• server is GPLv2
• client libraries are BSD licensed and are fresh implementations

We had the complete okay from Sun to have libdrizzle be BSD licensed and for us to work on that.

So, what impact does enabling the slow query log have on MySQL?

I decided to run some numbers. I’m using my laptop, as we all know the currently most-deployed database servers have mulitple cores, SSDs and many GB of RAM. For the curious: Intel(R) Core(TM) i7-2620M CPU @ 2.70GHz

The benchmark is going to be:
mysqlslap -u root test -S var/tmp/mysqld.1.sock -q 'select 1;' --number-of-queries=1000000 --concurrency=64 --create-schema=test

Which is pretty much “run a whole bunch of nothing, excluding all the overhead of storage engines, optimizer… and focus on logging”.

My first run was going to be with the slow query log on. I’ll start the server with mysql-test-run.pl as it’s just easy:
eatmydata

Just for the pure insane fun of it, I accepted the challenge of “what can you do with the text format of the schedule?” for BarCampMel. I’m a database guy, so I wanted to load it into a database (which would be Drizzle), and I wanted it to be easy to keep it up to date (this is an unconference after all).

So… the text file itself isn’t in any standard format, so I’d have to parse it. I’m lazy and didn’t want to leave the comfort of the database. Luckily, inside Drizzle, we have a js plugin that lets you execute arbitrary JavaScript. Parsing solved. I needed to get the program and luckily we have the http_functions plugin that uses libcurl to

Why is there no index for CSV files?  Indexes are very simple.

If the first column of your CSV file is in sorted order you can do a binary search to find your data.  But what if you need to find data in the second or third column?

If you have a separate index file pointing to the first byte of each line you could seek to that position in the CSV file and get your data.  Given a file with only your needed column and the byte offset and length of the line you can search the index to find the pointer to the position in the CSV file.

SAMPLE DATA
“record”,”title”,”data”
1,”test1”,”data1”
2,”test3”,”data3”
3,”test2”,”data2”

SAMPLE INDEX
“test1”,24,17
“test2”,58,17
“test3”,41,17

I recently released a new version of the Bazaar plugin for Jenkins. This release was inspired by a problem we noticed at Percona. It is:

• run “bzr revert” after a pull, as if you have a directory that is removed and re-added while having unknown files in said directory (e.g. build artifacts), you would end up in a very bad place (this is a BZR bug, so we work-around it with a “bzr revert”).

The update has already appeared in the Jenkins update centre, so you should already be able to upgrade to it.

From the desk of your new Bazaar plugin for Jenkins maintainer, I give you Version 1.18.

This release has two good bug fixes:

• UI fix for checkout option (JENKINS-12261)
• Auto-recover from corrupt BZR branches (e.g. bzr branch/checkout killed at inopportune moment) by cleaning the workspace and trying again (this is now default behaviour, best used with the Jenkins SCM retry count feature being > 1)

We’ve been running the same code as this release at Percona for about 2 months now (the second bugfix was one I wanted to test first before submitting upstream). This is the big fix that fixed all our problems with using bazaar with Jenkins in a large deployment.

For Drizzle and for all of the projects we work on at Percona we use the Bazaar revision control system (largely because it’s what we were using at MySQL and it’s what MySQL still uses). We also use Jenkins.

We have a lot of jobs in our Jenkins. A lot. We build upstream MySQL 5.1, 5.5 and 5.6, Percona Server 5.1, Percona Server 5.5, XtraBackup 1.6, 2.0 and 2.1. For each of these we also have the normal trunk builds as well as parameterised ones that allow a developer to test out a tree before they ask for it to be merged. We also have each of these products across seven operating systems and for each of those both x86 32bit and 64bit. If we weren’t already in the

In early 2006 Paul Hurley (ideeli’s CEO) and I (Mark Uhrmacher, CTO) were thinking about a new business. We had the idea to create a community based around great deals for Women’s fashion products where we saw a great deal of potential for great content and product sales. Now, over five years later, we’ve realized much of that vision. Our business success has been chronicled over the years in several places (see here and here). Though we’re very proud of our achievements there, that isn’t what this blog is about.

Insatiable Demand is about a mostly untold story. Over the past five-plus years we’ve built a phenomenal technology platform and team. From two people and three servers to a

The Issue

Although it is possible to create a view with a nonexistent DEFINER account, an error occurs when the view is referenced if the SQL SECURITY value is DEFINER but the definer account does not exist.

The Problem