The Case Against pgvector | Alex Jacobs
What happens when you try to run pgvector in production and discover all the things the blog posts conveniently forgot to mention
Summary
VectorChord indexes 100 million 768-dimensional vectors in 20 minutes using 12 GB memory on a 16 vCPU machine, compared to pgvector's 40 hours and 200 GB.
Optimizations target three phases: hierarchical K-means plus dimensionality reduction cut initialization from 30 to 8 minutes and memory from 135 GB to 23 GB; reduced contention speeds insertion from 420 to 9 minutes; parallelized compaction drops from 8 to 1 minute. These enable indexing on cheaper instances like Amazon i7i.4xlarge without GPUs.