Administration Session

Identify Running PostgreSQL Autovacuum Worker Sessions Autovacuum lag is a slow accumulation. Every UPDATE rewrites the row and creates a new HOT chain, the launcher falls behind during write spikes, and over weeks a busy OLTP cluster ends up with three workers stuck on a handful of huge tables while smaller ones wait …

Cancel vs Terminate PostgreSQL Backends: What Every DBA Should Know PostgreSQL gives you two tools for dealing with problem backends: pg_cancel_backend() and pg_terminate_backend(). They sound similar but behave very differently. Using the wrong one can disrupt users unnecessarily, or leave a problematic connection in …

Detect PostgreSQL Transaction ID Wraparound Before It Causes Downtime PostgreSQL assigns a transaction ID (XID) to every write transaction. These IDs are 32-bit integers, so the counter wraps around after about 4 billion transactions. Because IDs are compared modulo 2^32, each ID has two billion IDs that count as older …

Find PostgreSQL Tables That Need VACUUM FREEZE PostgreSQL uses transaction IDs (XIDs) to track which rows are visible to which transactions. Over time, these IDs age. When a table's oldest unfrozen XID gets too old, PostgreSQL triggers an aggressive autovacuum to freeze it. This is controlled by the …

How to Monitor PostgreSQL Index Build Progress Building an index on a large table can take minutes or even hours. Without progress tracking, it is hard to know if the build is almost done or barely started. PostgreSQL 12 introduced the pg_stat_progress_create_index view to fix this. It shows real-time progress for any …

How to Find Idle in Transaction Sessions in PostgreSQL An idle-in-transaction session is a database connection that has started a transaction but is not currently running a query. It is just sitting there, holding the transaction open. This is different from a regular idle connection, which has no open transaction. …

Monitor Slow Running Queries in PostgreSQL with pg_stat_activity An application hangs, the connection pool fills up, and somewhere a statement has been running for minutes. pg_stat_activity shows it for every backend on the server: how long the current query has been going, which role and database it belongs to, and …

How to Analyze PostgreSQL Query Cache-Hit Ratio Using pg_stat_statements Purpose Measuring the cache-hit ratio of your PostgreSQL queries is essential for understanding and optimizing how efficiently your database serves data from memory versus disk. This article explains how to use the pg_stat_statements extension to …

Identify Idle PostgreSQL Connections: Keep Your Database Clean A session in state idle since 09:14 is a client that connected, finished its work and never hung up. pg_stat_activity has one row per server process, and its state and state_change columns list every session like it. A short query against that view lists …

Identifying Blocking PostgreSQL Queries: A Guide for Database Administrators This article explores a PostgreSQL query designed to identify currently blocked database queries and the processes (identified by PIDs) responsible for blocking them. This information is crucial for database administrators troubleshooting …