Postgres Auditing in 150 lines of SQL
We have a new business system we are trying to build that has a <i>lot</i> of very granular auditing and versioning requirements throughout, and this is where I started looking.<p>After a while of screwing with this kind of approach, I realized that the number of different types of objects involved was going to cause an explosion in the number of related auditing and versioning tables. Keeping track of not only who changed something but also the exact facts they changed (such that you could revert as needed) requires a lot of additional boilerplate in each instance.<p>So, I made a pretty big gamble and went all-in on an event-sourced abstraction where everything is written to 1 gigantic append-only log of events. Turns out, this was worth it in our case. As long as everything has a timestamp and you have a way to refer to specific log entries (i.e. by offset), you basically have a complete solution. The hard parts are handled by a JSON serializer and gzip. We use in-memory indexes that are simply long/long dictionaries that map an object identity to a physical log offset.<p>The only downside with what I have proposed is that there is no garbage collection or cleanup possible. At this time, this is actually a highly-desirable property of the system. Disk space is cheap. Losing 3 weeks of work to an accidental button click is not.