Radim Marek: How TABLESAMPLE picks rows
Most exploratory questions against a large table only need a rough answer, but without an index on status , even "roughly how many shipped orders" costs a full scan.
Executive Summary
Most exploratory questions against a large table only need a rough answer, but without an index on status , even "roughly how many shipped orders" costs a full scan. On the two-million-row orders table, Postgres has to read every single 8 kB page, all 18,085 of them (141 MB), just to count matching rows. EXPLAIN (ANALYZE, BUFFERS) SELECT count ( * ) FROM orders WHERE status = 'shipped' ; Aggregate Buffers: shared hit=18085 -> Seq Scan on orders (actual rows=500000.00 loops=1) Filter: (status = 'shipped'::text) Rows Removed by Filter: 1500000 Execution Time: 56.188 ms shared hit=18085 is one buffer access per page, every page found already in memory ( Reading Buffer...
Database Engine & Storage Subsystem Architecture
From an OLTP/OLAP systems architecture, storage tiering, and data durability perspective: - **Zero-Vendor Lock-in Formats:** Leveraging open specifications (e.g. Parquet, Iceberg) ensures multi-engine interoperability without ingestion lock-in. - **Vector & In-Memory Throughput:** Modern memory layouts and SIMD-accelerated execution pipelines minimize latency in real-time retrieval. - **Distributed Resiliency:** Decoupled storage and compute layers enable elastic horizontal scaling with strict ACID guarantees.
Impact on the Open Ecosystem
Empowers data engineers with open, self-hosted alternatives to monopolistic cloud database providers.