PGConf.Russia 2022

This talk covers the Oracle-to-Postgres Pro migration project for the billing system of the Federal State Unitary Enterprise “State Air Traffic Management Corporation of the Russian Federation” employed to collect the air navigation charges for the use of airspace.

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.

Our talk reviews the modern tools for administering PostgreSQL. It also covers the DBMS's performance bottlenecks and provides approaches to resolving the related issues. The presentation tackles the problems that occur while Oracle to Postgres migrations including the following: performance tuning tools (the analogues of AWR and ASH); monitoring tools (the analogues of Cloud Control); ensuring high availability and reliability of the database (grid infrastructure analogues); known "database performance bottlenecks"; an overview of options for technical support options SLAs.

Previously, we have explained the internals of Avito, discussed, where and how we store your classifieds, and how they appear on the search results. In the recent 3-4 a lot has changed in Avito. We got rid of logical replication, stopped using standby servers for reads, removed nearly all stored procedures and our custom failover solution, migrated all our classifieds into a sharded DBMS, switched from the monolith app to microservices. I'll explain why we made such decisions, list some of the problems we encountered and describe the current state of our development process.