~/talk

Learned Indexes in PostgreSQL: Theory & Implementation

Talkat FOSSASIA PGDay 2025 · on Friday, 2025-03-14· at 14:45· Hall 2· [databases, machine-learning]

Claims a learned-index prototype for PostgreSQL that trains models externally (using TensorFlow compiled to C++), then deploys them alongside B‑trees as failback. Recreated RMI/Alex-style multi‑stage models, benchmarks show much smaller storage footprints and up to 2–3× speedup on read-heavy, skewed datasets in prior papers, but the prototype highlights problems with updates, outliers, last‑mile accuracy and planning. Integration touches the index access method API, requires sampling, external training, runtime monitoring and periodic retraining rather than in‑server on‑the‑fly learning.

AI-written summary · about

  1. 0:00Introduction and motivation
  2. 5:00What are learned indexes
  3. 12:24Studies and models overview
  4. 17:43Why PostgreSQL for learned indexes
  5. 21:32Implementation approach
  6. 25:47Q&A and closing remarks
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