PGConf.Russia 2022

Many books end with a wedding, but the reader has no idea about the future life of the heroes except that they lived happily ever after. In 2019, we successfully migrated distributed our railway application from Oracle 11g SE to vanilla PostgreSQL 11.9. But our story did not end with this successful migration - life went on, and sometimes we got startled because of "surprises". We encountered a number of problems, some of which were solved by reorganizing the data, some disappeared after we changed our stored procedures, and some got resolved after tuning the PostgreSQL parameters. Solving our problems would be impossible without the logging and profiling system built into our DB application. Our talk covers the examples of successful detection and resolving of the performance issues that occurred in our PostgreSQL-based application.

During my career, I've seen a lot of code, and very often I faced inaccuracies in handling dates and times. Sometimes the parties got discrepancies in the monthly reports due to such inaccuracies; or daily reports were different for Moscow and SFO, etc. I wouldn't call it a serious problem, but it's annoying and time-consuming. In all cases, such issues occur because of neglectful handling of dates and times. In my presentation, I will discuss how we can avoid it.

The more tables are involved with the query, the more difficult it is for the scheduler to choose a suitable execution plan (both time and memory usage increase). How can we "tell" the planner that it is better to connect this pair of tables first, and the rest can be connected later? What if we see that a part of our query can be improved, but the optimizer does not do this. In my presentation, I will talk about managing the order of connections. I will explain how we can influence the formation of a query plan using the standard "vanilla" PostgreSQL methods.

SPQR is a lightweight OLTP sharding solution written in Go. In this talk, I'm going to discuss design decisions that led us through FDW-based sharding, CustomNode-based sharding, C-implemented lightweight query routing, and finally to SPQR design.