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 wasn’t really …[Read more]
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.
- Auto Recovery Routine (startup option)
- Tokyo Cabinet’s Transaction API (table-specific option)
The …[Read more]
Last month while being at the MySQL Conference, several people asked me about the status of BlitzDB. Specifically, they were interested in when I’ll release BlitzDB. Fair enough – I’ve been working on this project long enough for people to start questioning this.
The answer is, BlitzDB is done in terms of implementing the design. Right now it’s about finding bugs, fixing it and testing BlitzDB’s stability under concurrent load. Thanks to the motivation boost I gained at the conference, I’ve now fixed the bugs that were slowing me down and I’m gradually adding more tests into BlitzDB’s test suite. I consider BlitzDB’s initial release to be the day it gets merged into Drizzle’s trunk. This is almost ready as BlitzDB seems to be building fine on Drizzle’s Build Farm infrastructure. However, I won’t move to the next step until I’m satisfied with BlitzDB’s stability.
Yesterday I spent some time doing some …[Read more]
Learned something new from my own bug in BlitzDB today. The problem was that writing a DATE column index would always return a duplicate key error (regardless of what I feed it). There are two suspicious candidates that can cause this.
- Comparison Function has a defect.
- Key Generator has a defect.
The latter suspect was going to be tricky if it was true since BlitzDB currently uses Drizzle’s native “field packer” (except for VARCHAR) inherited from MySQL. This would mean that Drizzle’s field system has a bug in it which was somewhat difficult to believe. Furthermore, you should always blame yourself before you start suspecting other people’s code. So, I decided to look into the comparison function which was completely written by me. Turned out that’s where the bug was.
Allow me to quickly clarify what I mean by “comparison function” in this context. …[Read more]