Connection pooling with pgBouncer, EXPLAIN ANALYZE, partial indexes.

PostgreSQL — MVCC, JSONB, and Index Types

PostgreSQL is a battle-hardened RDBMS with MVCC (Multi-Version Concurrency Control) for non-blocking reads. Every write creates a new row version; vacuuming reclaims dead tuples. Index types include B-tree (default), GIN (JSONB/full-text), GiST (ranges/geo), and BRIN (time-series). Connection pooling via pgBouncer is essential — Postgres spawns a process per connection (~5MB each). EXPLAIN ANALYZE reveals actual vs estimated row counts, helping diagnose missing indexes and planner mistakes.

Interactive Pipeline Flow

UnderstandImplementOptimise

🔌 Connect — pgBouncer pool

pgBouncer pools connections in transaction mode — underlying Postgres sees only max_connections (typically 100). Apps can have thousands of clients with 10 Postgres connections.

Architecture Diagrams

Choosing the right Postgres index type for your query pattern.

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Key Design Decisions

🔌Always use connection pooling

Postgres allocates ~5MB per backend process. 500 direct connections = 2.5GB RAM just for process overhead. Use pgBouncer in transaction mode.

📑GIN for JSONB queries

For JSONB columns with @> (contains) queries, create a GIN index: CREATE INDEX ON docs USING GIN (data). Without it, every query is a full table scan.

🧹Watch autovacuum on high-churn tables

Tables with many UPDATEs accumulate dead tuples. Monitor pg_stat_user_tables.n_dead_tup. If autovacuum lags, tune autovacuum_vacuum_scale_factor or run VACUUM manually.

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