PGConf.Russia 2025

The execution time of SQL queries depends on factors like indexes and up-to-date statistics. In most cases, optimizing slow queries helps resolve database performance issues.

But what if classic query optimization doesn’t work? What if the system keeps behaving unpredictably — or worse, crashes, leading to frustration, panic, and even despair?

In this talk, we’ll explore how Postgres Professional’s performance engineers tackle these challenges, look at the tools they use, what’s still missing, and where PostgreSQL performance optimization is headed

This talk will cover key aspects of migrating from SQL Server to PostgreSQL, with a focus on converting stored procedures, triggers, views, functions, and other database objects. We’ll discuss the unique characteristics of each database system that can complicate code conversion, as well as unexpected factors that impact performance and correctness.

The session will be valuable for both experienced database professionals and those new to database migrations.

Diagnostic Methods: Analyzing the Issue of Long CREATE DATABASE Execution

This talk covers two cases of long CREATE DATABASE execution in PostgreSQL 11, which, in a Corosync/Pacemaker cluster configuration, caused node failover due to a monitoring timeout from the clustering software. The first case is related to a large shared buffers size, while the second involves the use of the WITH OWNER option during database creation and a large pg_shdepend system table (a feature of using the jBPM software).

This talk explores the challenges we encountered — and solved — while migrating massive databases from Oracle to PostgreSQL.

One of the most complex aspects of this process was rebuilding foreign keys (FKs). To overcome these challenges, we had to dive deep into the internal workings of FK creation and validation.

Key topics include:

Does ALTER TABLE ... ADD CONSTRAINT ... FOREIGN KEY have an execution plan?

Can an ordinary user influence this process?

What locks are applied during FK creation and validation?

Also, we’ll introduce a first-principles method for investigating performance issues, applying it to a real-world FK creation bottleneck.