pg_wal_visualizer

Local stack scaffolding for a Postgres WAL observer.

Stack

• Rust stable toolchain plus a dependency manifest in Cargo.toml
• PostgreSQL 16 running locally from the repo
• Nix flake dev shell for reproducible setup
• just recipes for common workflow commands

Bootstrapping

nix develop path:. -c zsh
just db-init

The flake shell exports:

• PGDATA=$PWD/.local/postgres
• PGHOST=$PWD/.local/postgres
• PGPORT=5433
• PGUSER=postgres
• PGDATABASE=pg_wal_visualizer
• DATABASE_URL=postgresql://postgres@127.0.0.1:5433/pg_wal_visualizer

Database lifecycle

just db-start
just db-stop
just db-reset

Schema and seed data live in scripts/sql/schema.sql and scripts/sql/seed.sql.

Continuous WAL-producing load

RATE_PER_SEC=5 BATCH_SIZE=20 MODE=mixed just load

Supported modes:

• insert
• update
• mixed

This keeps writing to the seeded events table so the future visualizer has changing WAL volume to observe.

Rust crates chosen for the setup

• tokio: async runtime for polling loops
• sqlx: direct Postgres access without an ORM
• clap: CLI commands like inspect live or run experiment
• tracing and tracing-subscriber: structured logs during experiments
• serde and serde_json: payload and config serialization
• chrono, uuid: common DB-facing types

These are listed only as workspace dependencies for now. No Rust app logic is scaffolded.