postgres
Postgres 19 adds SQL/PGQ graph queries over the tables you already have, an atomic ON CONFLICT DO SELECT upsert, and REPACK CONCURRENTLY that returns disk space without locking the table. Here is what each one replaces, with working SQL and the limits the release notes do not shout about.
architecture
OpenAI serves over 800 million weekly ChatGPT users without database sharding. Inside the architecture: a single primary PostgreSQL, cascading read replicas, aggressive caching against thundering herds, and connection pooling pushed to its limits.
postgres
PostgreSQL lock timeouts strike during long migrations and complex transactions. How lock_timeout and statement_timeout actually work, quick fixes at the database role level, managing timeouts in Rails migrations, and global protection with StrongMigrations.
PostgreSQL database size checks in a few simple SQL queries: list all databases with pg_database and pg_size_pretty, then break down the biggest tables in a schema, indexes included. Spot what eats disk space before it slows backups and raises infrastructure costs.
Idle PostgreSQL connections eat memory and can hit the max_connections limit, blocking your app. How to find old sessions in pg_stat_activity, close them safely with pg_terminate_backend, and automate the cleanup so hanging connections never pile up again.
PostgreSQL trigram similarity finds records despite typos: enable pg_trgm, run similarity queries from Rails, tune the threshold, order results by score, and wrap it all in a reusable scope. Great for fuzzy search and duplicate detection without external tools.
PostgreSQL 17 finally implements the SQL/JSON standard: constructors like JSON_OBJECT and JSON_ARRAYAGG, query functions JSON_EXISTS and JSON_QUERY, and the star of the release, JSON_TABLE, which turns JSON into rows, shown on a real IoT data example.