Behzad

pg_stat_activity

pg_stat_activity is one of PostgreSQL's most important system views (in the pg_catalog schema). It provides a real-time snapshot of all server processes (backends) and their current activity on the database instance. Each row represents one backend process (typically one client connection/session, plus some

How to Route Reads to Replicas and Writes to Primary in PostgreSQL

1. Replication Type in Postgres PostgreSQL uses physical streaming replication (the standard and most common method). * One Primary (read-write) + One or more Replicas (read-only hot standbys). * This is a primary-replica (master-slave) architecture — not active-active. FeatureDetailsActive-ActiveNo. Only the primary accepts writes. Replicas are read-only.

Explaining pg_stat_activity

pg_stat_activity is one of PostgreSQL's most important system views (in the pg_catalog schema). It provides a real-time snapshot of all server processes (backends) and their current activity on the database instance. Each row represents one backend process (typically one client connection/session, plus some

CAP Theorem

The CAP Theorem (Consistency, Availability, Partition Tolerance) is a fundamental principle in distributed systems, introduced by Eric Brewer in 2000 and later formalized. It states that in a distributed database (one that runs across multiple nodes/servers), it is impossible to simultaneously guarantee all three properties perfectly, especially during network