Activity Monitor

The Activity Monitor is a live view of a PostgreSQL server built on pg_stat_activity. It shows who is connected, what is running, which sessions block each other, and lets you cancel queries or terminate sessions.

Opening the monitor

In the Database Explorer, right-click a PostgreSQL data source or database and choose Activity Monitor. The action is also available in Find Action (⌘⇧A, Ctrl+Shift+A on Linux and Windows).

The monitor opens as a non-modal window, so you can keep working in consoles while it refreshes.

Toolbar

• Live status, server version and database.
• Pause and refresh buttons. The refresh interval is Every 1 s, 2 s, 5 s or 10 s, or you can pause polling.
• A filter field for PID, user, application or query text.
• Hide idle hides idle sessions.
• This database limits the list to the current database.
• Background includes background server processes.

Server counters

A single line under the toolbar summarizes the server:

Counter	Meaning
Connections	Open connections compared to max_connections
Active	Sessions running a query
Waiting on locks	Sessions waiting for a lock
Idle in transaction	Sessions with an open transaction and no running query
Blocked	Sessions blocked by another session
Transactions/s	Transaction rate with a small chart, computed from pg_stat_database differences; counter resets are skipped

Only values that indicate a problem are colored: connection usage above 70%, locks, and transactions open for more than a minute. Tooltips give details such as the longest running query and the oldest transaction.

Sessions over time and breakdown

• Sessions over time charts session states (active, waiting, idle in transaction, idle) for the last five minutes. Hover a sample to see its values.
• Breakdown groups sessions by State, User, Application, Database or Wait event. Click a bar to filter the session list.

Blocking tree

When sessions wait for locks, the Blocking section shows a tree built from pg_blocking_pids: each blocker with the sessions waiting on it, their state, duration and query. Click a PID to select that session.

Session list and details

The Sessions table lists PID, State, User, Database, Application, Client, Wait, Duration and Query. Click a column header to sort. Each row has a state badge and a duration bar.

Select a session to see its details:

• the full query with syntax highlighting,
• connection, query start, transaction age and time in the current state,
• the wait event and transaction identifiers,
• who blocks this session and whom it blocks, as clickable PIDs.

Actions for the selected session:

Action	Effect
Cancel Query	Calls pg_cancel_backend to cancel the running query
Terminate Session	Calls pg_terminate_backend to end the session
Open in Console	Opens the query in a new console
Copy Query	Copies the query text

Cancel Query and Terminate Session ask for confirmation.

Accuracy

• Durations are computed by the server against its own now(), so a clock difference between your computer and the server does not distort them.
• The monitor's own session is excluded from the list.
• If a refresh fails, the last sample stays on screen with a red notice.
• Queries hidden by the server (<insufficient privilege>) are labeled as such, with a note about the pg_read_all_stats role that grants access to them.

Polling and load on the server

The monitor is designed to stay light on the server it watches:

• It uses one persistent connection per monitor and two lightweight queries per sample.
• The next sample starts only after the previous one has finished, so a slow server never receives a backlog of queries.
• pg_blocking_pids is evaluated only for sessions that wait for a lock, and pg_locks is read only when some session is waiting for one. Both operations briefly lock the server's lock manager.
• A sample has a 15 s timeout. After consecutive errors, the interval doubles up to 30 s.
• A minimized monitor window does not poll the server.

On the client side, the blocking tree, breakdown, summaries and query highlighting are computed once per sample or filter change, and the session table draws only the visible rows.