PGConf.Russia 2023

Primary key generation is a known issue quite efficiently though not ideally solved by sequences. There are still problems with distributed generation, real uniqueness and predictability. Initially, UUID was not intended for use as a DBMS key, but its new versions (6, 7 and 8) make it quite convenient to use them as both synthetic and natural keys.

ORM libraries are widely used in backend development – let's take this for granted. ORM libraries are improving, developers are learning from their own and others' mistakes, and many have learned to write code for ORM that generates quite optimal queries for typical operations. Yet, limited functionality of existing tools is another problem related to ORM. This is especially true for Postgres, which has a lot of operators and constructs (both in the core and in extensions) that go beyond the SQL standard.

With LinqToDb ORM library you can write extensions that implement any SQL operator or construct very easy, literally using just one line. Full-text search, KNN, CTE (including recursive ones), working with arrays and jsonb, array_agg and jsonb_object_agg, table functions and LATERAL JOIN - all this can be easily used in ORM, which I will demonstrate during this talk!

Delta migration case using Debezium is considered in details as well as the process of change data capture, sinking, applying configurations and load testing.

The importance of sharding is now colossal. The size of today's databases exceeds 100 terabytes, scaling up vertically, and adding replicas containing a complete physical copy of the database is becoming difficult, especially when computational resources are scarce. Database sharding is a way to scale horizontally by partitioning data between compute nodes that are independent of each other.

In the PostgreSQL world, there are well-known scaling tools - CitusDB, and Greenplum - as well as new generation solutions - Cockroach DB, Yugabyte DB, SPQR, and Shardman.

In this talk, we will discuss the difference between these implementations, the advantages, and disadvantages of these solutions, examine the current state of implementation of sharding in vanilla PostgreSQL, and also touch on another important topic - providing data integrity and consistency guarantees across a distributed cluster.