PgConf.Russia 2016

The talk will be articulated around all the traditional arguments to "how chose PostgreSQL over other choices in the database domain"... But also, and that's quite new in the comunity, what are the consequences of this choice. Because the PostgreSQL adoption brings adoption of other things like Linux, but also, Open Source thinking, the fast pace of PostgreSQL will command new methods of validation the company must adapt to... etc.

PostgreSQL includes several index types: GiST, SP-GiST, GIN, and of course, the regular B-tree. DBAs are familiar with using each of these for specific use cases, GIN for full-text search, GiST for geometrical data, and so on, but how do they work internally? What makes them suitable for the cases they're typically used for?

In this presentation, I will walk through the internal structure of each of these index types, explaining what strengths and weaknesses each one of them have.

The talk is about PostgreSQL clusters using streaming replication and pgpool-II, which are quite popular in Japan. Plus, the next version of pgpool-II will be released this winter, so the talk will be about what's new in the version.

Postgresql's buffer manager has parts where it's showing its age. We'll discuss how it currently works, what problems there are, and what attempts are in progress to rectify its weaknesses.

• Lookups in the buffer cache are expensive
• The buffer mapping table is organized as a hash table, which makes efficient implementations of prefetching, write coalescing, dropping of cache contents hard
• Relation extension scales badly
• Cache replacement is inefficient
• Cache replacement replaces the wrong buffers