A few months ago I wrote a tool that verified MySQL and Drizzle protocol compatibility, along with testing for all sorts of edge cases. In analyzing protocol command interactions in mysqld, I found that the MySQL server will happily read an infinite amount of data if you exceed the maximum packet size while using a special sequence of protocol packets. The reasoning behind this behavior is so that the server can be polite and flush your data before sending a “max packet exceeded” error message, but perhaps there should be a limit to one’s politeness. What’s more interesting is that you can do this during the client handshake packet without authorization, so anyone could do this to any open MySQL server. The appropriate thing to do here would be to set some maximum limit of data to read and force a connection close when it is reached, otherwise your bandwidth and CPU could be consumed (essentially a DoS attack).

This portion of code …

A new release of the PrimeBase Media Streaming daemon is now available for download at
http://www.blobstreaming.org .

This release doesn't contain any major new features just some bug fixes and a lot of house keeping changes.

If you look at the download section on http://www.blobstreaming.org you will see that there are now more packages that can be downloaded. I have separated out different client side components from the PBMS project and created separate launchPad projects for each one. You can see them listed in the "Related Links" side panel to the right of this post.

• The "PBMS Client Library" facilitates communication with the PBMS daemon. This library is independent of the PBMS daemon's host server and can be used to communicate with a PBMS daemon hosted by …

Crash Safety is a big deal in the database league. Lack of durability can lead to all sorts of terrible things upon a catastrophic event. Many projects, especially in the so called NoSQL world compromises crash safety in return for higher QPS. The argument there is that the availability of the overall system should be accomplished by replication since a database server can’t be rescued if the physical disk breaks. I happen to agree with this philosophy but I am also aware that this isn’t a correct answer for everyone. So, what will I do with BlitzDB?

Several relational database hackers have pointed out that BlitzDB isn’t any safer than MyISAM since it doesn’t guarantee crash safety. This is currently true but I plan on making BlitzDB much safer than MyISAM by providing following features.

1. Auto Recovery Routine (startup option)
2. Tokyo Cabinet’s Transaction API (table-specific option)

The …

So I sometimes get asked if we funnel back bug reports or patches back to MySQL from Drizzle. Also, MariaDB adds some interest here as they are a lot closer (and indeed compatible with) to MySQL. With Drizzle, we have deviated really quite heavily from the MySQL codebase. There are still some common areas, but they’re getting rarer (especially to just directly apply a patch).

Back in June 2009, while working on Drizzle at Sun, I found a bug that I knew would affect both. The patch would even directly apply (well… close, but I made one anyway).

So the typical process of me filing a MySQL bug these days is:

• Stewart files bug
• In the next window of Sveta being awake, it’s verified.

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I’m at OSCON this week. Come say hi and talk Drizzle, Rackspace, cloud, photography, vegan food or brewing.

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Head on over to http://lca2011.linux.org.au/ and check it out!

You’ve got until August 7th to put in a paper, miniconf, poster or tutorial.

Things I’d like to see come from my kinda world:

• topics on running large numbers of machines
• latest in large scale web infrastructure
• latest going on in the IO space: (SSD, filesystems, SSD as L2 cache)
• Applications of above technologies and what it means for application performance
• Scalable and massive tcp daemons (i.e. Eric should come talk on scalestack)
• exploration of pain points in current technologies and discussion on ways to fix them (from people really in the know)
• A Hydra tutorial: starting with stock Ubuntu lucid, and exiting the tutorial with some analysis running on my project.
• Something that completely takes me off …

If you haven't already heard PBMS is now part of the Drizzle tree.

Getting it there was a fair bit of work but not as much as I had thought it would be. The process of getting it to work with Drizzle and running it thorough Hudson has improved the code a lot. It is amazing what some compilers will catch that others will let by. I am now a firm believer in treating all compiler warnings as errors.

I am just in the process of updating the PBMS plugin so that it will build and install the PBMS client library (libpbmscl.so) as well as the plugin. The PBMS client library is a standalone library that can be used to access the PBMS daemon weather it is running as part of MySQL or Drizzle. So a PBMS client library built with Drizzle can be used to access a PBMS daemon running as part of MySQL and vice-versa.

There is also PHP extension for PBMS that is basically just a wrapper for the library. Currently this is …

Some of you may have noticed that blob streaming has been merged into the main Drizzle tree recently. There are a few hooks inside the Drizzle kernel that PBMS uses, and everything else is just in the plug in.

For those not familiar with PBMS it does two things: provide a place (not in the table) for BLOBs to be stored (locally on disk or even out to S3) and provide a HTTP interface to get and store BLOBs.

This means you can do really neat things such as have your BLOBs replicated, consistent and all those nice databasey things as well as easily access them in a scalable way (everybody knows how to cache HTTP).

This is a great addition to the AlsoSQL arsenal of Drizzle. I’m looking forward to it advancing and being adopted (now much easier that it’s in the main repository)

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One extremely useful feature in MySQL is the "slow query log". In the stock distribution, it records every query that takes more than 1 second to execute, and every query that requires a full table scan. A useful part of the Percona patches extend this feature to measure sub-second slow queries, which became important as machines got faster.

When someone asks "Why is the database slow?", the first counter question to ask is "What's in the slow query log?"

One of the confusing parts of administering MySQL is that the "query log" and the "slow query log" are different things. They have different controlling options, and different log formats.

When I ripped out and replaced the logging system during the Drizzle fork, I took these two logging systems, which were implemented as completely separate code, and merged them together. There is now only the "query log", but it can be filtered in-process to only …

Monty’s talk at Velocity 2010 seemed to go down really well (at least from reading the agile admin entry on Drizzle). There are a few great bits from this article that just made me laugh:

“Oracle’s “run Java within the database” is an example of totally retarded functionality whose main job is to ruin your life”

Love it that we’re managing to get the message out.

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