Pg_stat_activity

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 …

Understanding PostgreSQL Wait Events for Performance Analysis Every active PostgreSQL backend is either executing work or waiting. When a session waits, PostgreSQL records the reason in pg_stat_activity using two columns: wait_event_type and wait_event. Aggregating these across all sessions gives a clear picture of …

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, which means they can only count up to about 2 billion. When the counter gets close to the limit, PostgreSQL must freeze old transaction IDs to …

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. …

Kill Idle PostgreSQL Sessions with SQL These PostgreSQL scripts terminate idle sessions that have been inactive for more than 15 minutes. Two variants are provided: one that targets idle sessions across all databases on the server, and one scoped to only the currently connected database. Purpose and Overview Idle and …

Count PostgreSQL Sessions by State This PostgreSQL query returns a count of all server sessions grouped by their current state. It gives a fast at-a-glance view of how connections are distributed across active, idle, and problematic states. Purpose and Overview PostgreSQL tracks the state of every backend connection in …

PostgreSQL Query Planning Settings Query Guide This PostgreSQL query retrieves all query tuning and statistics collection settings from the pg_settings system view. These parameters control how the query planner selects execution strategies, estimates costs, and collects runtime statistics. Purpose and Overview The …