Pondělí květen 28, 2007

PGCon 2007

PGCon 2007 went ahead last week in Ottawa. It started on Monday May 21st with two days of tutorials. I attended only Niel Conway's tutorial Introduction to Hacking PostgreSQL. Niel presented how to write PostgreSQL code, what kind of tools is useful for debugging and he also described how to use memory management and handle errors. He mentioned DTrace as a good tool for debugging, but he does not have experience with it. I had a few OpenSolaris Developer Express Starter kits and I gave him one copy.

Official registration started on Tuesday evening in Royal Oak pub. A lot of hackers and users were there when I came and they discussed a lot of topics.

My and Jim's mission there was to discuss PostgreSQL upgrade project. Nobody want to have eight versions of PostgreSQL in Solaris and there is not easy way how to upgrade from one version to another, especially when database is very big. We made decision that only on-fly upgrade, when new PostgreSQL version will understand old database structures, is correct. However, this solution requires a lot of changes in the current code and it is not possible start without wide acceptance. We started discussion with EnterpriseDB folks, because they work on PG Migrator tool. PG Migrator tool is useful for migration between 8.1 to 8.2, because there are mostly only catalog changes (disk layout is not touched exclude two datatypes). However for 8.2 to 8.3 migration PG Migrator is not suitable. It is designed as offline utility and conversion of Tera byte database disk structures take a long time. After hot discussion about technical details the fully integrated on-fly upgrade has been accepted as possible and correct solution.

I also had 5 minutes long lighting talk about it and a lot of people interested in this solution. Only two things are now necessary to do ... design and implementation.

We (Sun's folks) had also two other presentations. Jim Gates, Robert Lor, Josh Berkus and me presented Useful Solaris tools for PostgreSQL DBAs. I think there were over fifty attendants. Unfortunately, our presentation did not fit in one hour and we skipped SMF. People mostly interested in DTrace and ZFS features. Robert spent a lot of time after presentation with people who interested in DTrace and they wanted to learn more.

Julo Stroffek and Tomas Kovarik presented Execution plan optimization techniques. PostgreSQL uses genetic algorithm to determine execution plan for twelve and more tables join optimization. This algorithm is not optimal and Julo and Tomas presented summary of suitable optimization methods. Their presentation was accepted and PostgreSQL hackers now interest in real result. However, some pluggable interface for optimizer is first step in their effort.

There were a lot of excellent presentations and most of them are available on conference web site. If I could recommend one presentation Scaling PostgreSQL on SMP Architectures -- An Update is very interesting.

I think it was excellent conference and I'm looking forward to next year.