PostgreSQL JSONB Indexing Strategies for Mobile API Backends

--- title: "JSONB Indexing: GIN vs Expression Indexes for Mobile APIs" published: true description: "Learn why your PostgreSQL JSONB queries hit sequential scans at scale. Compare GIN, trigram, and expression indexes with EXPLAIN ANALYZE walkthroughs for mobile backends." tags: postgresql, api, performance, mobile canonical_url: https://blog.mvpfactory.co/jsonb-indexing-gin-vs-expression-indexes-for-mobile-apis --- ## What We Will Build In this walkthrough, I will show you exactly why your GIN index is not doing what you think it is, and how to fix it. We will run `EXPLAIN ANALYZE` against a 2M-row table, compare three indexing strategies side by side, and land on a hybrid model you can migrate to without downtime. By the end, you will know how to audit your JSONB queries, pick the right index type for each access pattern, and avoid the TOAST decompression trap that silently kills p99 latency. ## Prerequisites - PostgreSQL 14+ (examples work through PG 17) - A table with a JSONB column