PGConf.Russia 2025

Not a PgBouncer, But a Connection Pooler. Not Odyssey, But with Coroutines

If you’ve ever set up a high-availability PostgreSQL cluster, you’ve likely faced the challenge of redirecting traffic to the primary node after a failover.

Typically, this requires additional software to monitor cluster status and reroute traffic accordingly. To avoid a single point of failure, you may have had to implement failover handling within that layer. Additionally, you might have encountered PostgreSQL’s limitations on handling large numbers of concurrent client sessions, necessitating query pooling.

To solve these issues, we developed Proxima — a scalable, fault-tolerant proxy and connection pooler. Proxima automatically redirects traffic to the primary node and, in BiHA setups, seamlessly switches to a new primary in case of failure.

In this talk, I’ll cover why and how we built Proxima, the key architectural decisions behind the extension, and the

implementation details that enable it to handle 10,000+ concurrent client sessions.

We’ll also explore use cases and answer your questions.

The focus of the presentation is on the challenges of building an application solution on PostgreSQL, specifically a high-load analytical data warehouse. Using the case of the company EVRAZ, we will demonstrate the impact of applying the Data Vault methodology on PostgreSQL and Greenplum databases for developing a unified production performance system.

We will discuss the difficulties and solutions, showcasing query plans for tasks such as updating directories and handling large objects, along with optimization examples. We will highlight coding nuances, problems related to populating the model, and issues with querying from the model.

This session will be useful for those planning to use or already facing challenges with the Data Vault methodology and performance issues in DWH on the open-source stack. We will compare technical implementation options for the Business Vault model layer, considering the specifics of PostgreSQL and Greenplum.

We will also cover 5 real problems that arise when operating a DWH and their solutions:

1. Transferring Business Vault object assembly logic from PostgreSQL to Greenplum.
2. Slower ETL performance when building the current state of Business Vault in PostgreSQL.
3. Slower Data Lineage construction in PostgreSQL and Greenplum.
4. Slow satellite queries in Greenplum.
5. Slow queries with "IN" or "OR" in the Business Vault layer.

Two years ago, I spoke about data retrieval queries, where the LINQ to DB library offers almost limitless possibilities.

This talk is about data modification operations. LINQ to DB allows you to execute UPDATE + JOIN queries, INSERT FROM SELECT, supports the MERGE operator, row-level locking with SELECT FOR UPDATE, temporary table creation, and features a fast data insertion mechanism.

I will also discuss the linq2db. EntityFrameworkCore project — a solution for those who aren’t ready to leave EF Core but still want the capabilities of LINQ to DB. I’ll share our experience implementing LINQ to DB in a large-scale project.

What does a modern application developer need to transition from familiar cloud-based solutions to SQL databases?

This talk is a practical report on how we transformed an SQL database into a NoSQL-like solution with a developer-friendly interface. We’ll discuss:

What application developers expect from a data framework

How to implement declarative DDL, access control, and automation for reading and writing data

Simplified DML operations, pagination, and other essential features for application development