Most developers use PostgreSQL every day without knowing what happens under the hood when they run an INSERT. I wanted to find out. So I built pgstream — a tool that reads every database change in real time directly from PostgreSQL's internal log. What is the WAL? Every time you insert, update, or delete a row, Postgres doesn't immediately write to the actual data files. It first writes the change to a file called the WAL — Write Ahead Log. This is how Postgres guarantees nothing gets lost if the server crashes mid-write. I had read about WAL in docs before but never really understood why it existed until I started building this. It clicked when I realized — the WAL is basically a journal. Postgres writes every intention down first, then acts on it. Logical Replication and pgoutput WAL records are stored in raw binary. You can't just read them like a text file.…