PgConf.Russia 2020

I will share our experience of migrating a server application for Russian railways from Oracle 11g Standard Edition to vanilla PostgreSQL 11.5.
At the time of migration, the database contained about 200 stored procedures of over 60000 lines of Oracle PL/SQL code (which has been developed since 2006, that is, for more than 12 years), about 250 tables, and 50GB of data.
Starting with a prologue, we'll describe our adventures along the migration process, as well as pleasant and unpleasant surprises we encountered, and finally get to an epilogue and a happy end. The story is told on behalf of an Oracle user exploring Postgres.

Open-source maintainers face many challenges as projects grow. How to write more required features, fix more issues and have time to watch more pull requests? On the example of WAL-G(backup tool for PostgreSQL) I will tell you about how we solved these problems by launching a course of Open-source development at Ural Federal University, what we achieved and what will we do next.

Greenplum is a horizontal scalable database based on PostgreSQL core. It is used for OLAP workloads and a standard task is to quickly load or unload large amounts of data. The external data resources are usually another distributed systems. In this talk I will show how Greenplum can work with external data. What is the architecture and performance of external and foreign tables and how to handle streaming data. What will be changed in the next version. The examples of Kafka and ClickHouse connectors development.

I'll show an example of solving the problem of searching "similar" texts for one given text in big array using GiST index. The problem itself is not much important, but it is easy to understand. Using this problem as example, I'll show one of many methods of adapting GiST index for custom search problems. Maybe this talk will help you to solve other search problems.