Architectural Performance
\"Don't tune queries until you tune the hardware interface.\"
The PostgreSQL 18 AIO Subsystem
The single biggest advancement in 2026 is the native Asynchronous I/O (AIO) subsystem. By leveraging Linux `io_uring`, Postgres no longer blocks a worker process while waiting for the kernel to return data from the NVMe drive. This increases throughput for IO-bound analytical queries by nearly 2.5x without changing a single line of SQL.
B-tree Skip Scans & Multi-column Indexes
Traditionally, a composite index on `(a, b, c)` was useless if you only queried for `b`. In PG 18, Skip Scans allow the planner to \"jump\" through the index to find values of `b` even if the leading column `a` is not in the predicate.
This allows for \"Thick Indexes\"—you can cover more query patterns with fewer total indexes, drastically reducing **Write Amplification** and vacuum pressure.
UUIDv7: The End of Index Fragmentation
If you use UUIDv4 (random), your B-tree indexes are becoming fragmented. This cause massive I/O overhead. In 2026, we've standardized on **UUIDv7**, which is time-ordered.
Because UUIDv7 IDs are monotonic, new entries are always added to the \"right\" side of the B-tree, keeping the index clustered and avoiding expensive Page Splits. I've seen database sizes drop by 30% simply by migrating from random UUIDs to time-ordered ones.
Postgres 18 Tuning Checklist
- 01.Set `shared_buffers` to 35% of total system RAM for modern NVMe rigs.
- 02.Enable `huge_pages` if your database exceeds 16GB.
- 03.Tun `random_page_cost` to 1.1 (Standard for SSD/NVMe).