Postgre SQLAdvanced Study Notes

ACID and Isolation Levels

How PostgreSQL guarantees Atomicity, Consistency, Isolation, and Durability, and how the four SQL isolation levels trade off correctness against concurrency.

B-Tree Indexes Explained

Learn how PostgreSQL's default B-tree index works internally and why it is the right choice for equality and range queries.

Common Table Expressions

Learn how PostgreSQL's WITH clause structures complex queries into named, readable building blocks, including recursive CTEs for hierarchical data.

Connection Pooling with PgBouncer

Learn why PostgreSQL connections are expensive, how PgBouncer's pooling modes work, and how to configure and monitor it safely in production.

Constraints in Depth

A thorough look at PostgreSQL's constraint types -- PRIMARY KEY, FOREIGN KEY, CHECK, UNIQUE, NOT NULL, and EXCLUDE -- and how they enforce data integrity at th…

Data Types in Depth

A practical deep dive into PostgreSQL's rich type system, covering numeric precision, text vs. varchar, JSONB, arrays, and enum/domain types.

Deadlocks and How to Avoid Them

How PostgreSQL detects circular lock-wait dependencies, what it does when it finds one, and practical patterns to prevent deadlocks in application code.

GIN and GiST Indexes

Understand when to reach for GIN and GiST index types to accelerate full-text search, JSONB containment, arrays, and geometric or range data.

Index Maintenance and Bloat

Understand why indexes accumulate dead space over time, how to detect bloat, and the tools PostgreSQL provides to reclaim it safely.

Indexing Strategies

Practical guidance for deciding what to index, how to order multicolumn indexes, and how to validate index effectiveness in PostgreSQL.

Join Algorithms in PostgreSQL

Understand the three physical join strategies PostgreSQL can choose — nested loop, hash join, and merge join — and when each one wins.

Locking in PostgreSQL

The row-level and table-level lock modes PostgreSQL uses to coordinate concurrent writers, and how to inspect and reason about lock contention.

Logical Replication

Understand how PostgreSQL's publish/subscribe logical replication decodes row-level changes for selective replication, zero-downtime upgrades, and cross-versio…

MVCC Explained

How PostgreSQL's Multi-Version Concurrency Control lets readers and writers avoid blocking each other by keeping multiple row versions and using visibility rul…

Partial and Expression Indexes

Use partial indexes to index only a relevant subset of rows and expression indexes to index computed values, keeping indexes smaller and more targeted.

Partitioning Large Tables

Learn how PostgreSQL's declarative partitioning splits large tables into manageable pieces for faster queries, easier maintenance, and efficient data lifecycle…

PostgreSQL Architecture Overview

A tour of how PostgreSQL is built internally: the process model, shared memory, the write-ahead log, and the MVCC storage engine that together deliver durabili…

PostgreSQL Backup and Restore

Understand logical and physical backup strategies in PostgreSQL, including pg_dump, pg_basebackup, and point-in-time recovery.

PostgreSQL High Availability Patterns

Learn how to design a highly available PostgreSQL deployment combining replication, automated failover, connection routing, and backups to meet real RTO/RPO ta…

PostgreSQL Interview Questions

Prepare for PostgreSQL technical interviews with commonly asked questions on internals, transactions, indexing, and troubleshooting.

PostgreSQL Performance Tuning

Learn how to diagnose slow queries and tune PostgreSQL configuration, indexing, and query plans for production workloads.

PostgreSQL Quick Reference

A condensed reference of essential PostgreSQL commands, psql shortcuts, and system catalog queries for day-to-day work.

PostgreSQL vs Other Databases

Compare PostgreSQL against MySQL, MongoDB, and other popular databases to understand where it excels and where alternatives may fit better.

Reading EXPLAIN ANALYZE

Learn to interpret PostgreSQL's EXPLAIN ANALYZE output so you can tell what a query planned versus what it actually did, and use that gap to fix slow queries.