Ghosts of MySQL Past, Part 6: The engine revs

This week I’ve been writing based on my 2014 talk, which you can watch the recording of. Also see Part 1, Part 2, Part 3, Part 4 and Part 5. My feed feel off Planet MySQL for a bit so you may have missed those posts.

Netfrastructure was many other things apart from just a database engine, but the one part that was interesting to MySQL was the storage engine. One interesting thing about Netfrastructure was the inbuilt Java VM, which meant you could do all sorts of neat tricks right near the data and with Jim and Ann coming from much more feature complete databases, some parts of MySQL were going to be a little bit of a shock.

There was still work to be done on the Falcon engine itself, it wasn’t completely finished and ready to just drop in, even though you may have heard things like “to be completed later this year”.

There was also another experiment to see if MySQL could get a storage engine that wasn’t owned by somebody else: resurrect Gemini. Remember, it was GPL licensed now, and it could conceivably be updated to the latest MySQL versions. You can go and see the code for the Amira project on launchpad. Ultimately, this went nowhere, but it could have been an interesting story if this project got more resources. Ultimately, it was Falcon that got all the attention and effort.

This was going to be the ultimate triumph of the Pluggable Storage Engine Architecture, something that had been touted in presentations and marketing material for years. What really happened? Well, it took NDB (now MySQL Cluster) somewhere between two and four years before you could really say it was stable and free of many “obvious” bugs/unintended deviations in behavior. Would Falcon be any different?

In reality, the Falcon project unearthed all of the warts of the storage engine interface. There were many exchanges of “Is it really like that?”, “Yes, yes it is, sorry.”

The APIs (and I use the term loosely) between a storage engine and the database server were originally used to plug in ISAM and then MyISAM, and the first transactional store (InnoDB) required a bunch of hacks to work and the API was never cleaned up. When the third transactional engine came along (MySQL Cluster) – which was also a distributed engine – there were again no real fixes in the API, just more of the same work-arounds and oddness. So by the time Falcon came along, if you were lucky the API was merely just not what you’d expect. There were many, many situations where not only was the official documentation inaccurate, but you’d have to commit several gross layering violations just to get something rather fundamental to a transactional database working.

Arguably the worst thing was foreign keys, a requirement for the Falcon project. You had to implement your own SQL parser to get any information on foreign keys. Let’s not even get started on auto_increment – something which the correct behavior is pretty much completely undocumented.

Next, we’ll look at PBXT.

7 thoughts on “Ghosts of MySQL Past, Part 6: The engine revs

  1. Pingback: Ghosts of MySQL Past, Part 7: PBXT | Ramblings

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