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Understanding Garbage Collection (GC) and Stop-The-World (STW) in the JVM

Oct 14, 2025 · 7 min read · This guide explains — step by step — how the JVM’s garbage collector actually works.We’ll start from how memory is structured (Eden, Survivor, Old), move to what happens during a Minor GC, then see what Stop-The-World (STW) really means, and finally ...

Write-Ahead Logging (WAL) in PostgreSQL: How It Works

Sep 18, 2025 · 5 min read · PostgreSQL guarantees durability using Write-Ahead Logging (WAL). WAL ensures that once a transaction is committed, its changes survive crashes, even if the actual table or index pages were never written to disk at the time of failure. This article g...

How PostgreSQL VACUUM Works: Dead Tuples, FSM/VM, and Locking

Sep 16, 2025 · 5 min read · PostgreSQL uses MVCC (Multi-Version Concurrency Control).Each UPDATE inserts a new row version (xmin = current XID) and marks the old one dead (xmax = current XID).Each DELETE marks the row dead by setting xmax. Dead tuples remain on disk, still refe...

How PostgreSQL Decides Row Visibility with MVCC

Sep 13, 2025 · 4 min read · PostgreSQL implements MVCC (Multi-Version Concurrency Control) so that transactions see a consistent view of data while minimizing blocking.This design is central to PostgreSQL’s ability to balance consistency with concurrency. Tuple metadata: xmin ...

PostgreSQL Locks — A Detailed Guide

Sep 9, 2025 · 4 min read · PostgreSQL Locks — A Detailed Guide When working with PostgreSQL, understanding locks is essential for reasoning about concurrency and troubleshooting blocking queries. Postgres uses two main categories of locks: row-level locks and table-level locks...