Details - Blocking

Blocking – Details

The Blocking Details screen displays individual blocking events for a single SQL Server instance. Use this screen when investigating a specific blocking incident, tracing a chain to its root cause, or reviewing the lead blocker statement and victim sessions for a recurring event.

To open the Details screen, select a single instance from the Instance filter or click the action icon (3 vertical dots at the right end of the row) on a row in the Overview and select View Details.

Toolbar and Filter Controls

• Views — Apply a saved view configuration
• Tag — Filter by tags assigned to hosts, instances, or databases. Tags are user-defined groupings commonly used to identify business units, applications, environments, or dashboards. Filtering by tag targets all assets that share that tag. Tags are created and managed in the Tags section.
• Filters — Apply one or more filters from the filter panel
• Reset — Clear all active filters and return to the default view

The Filters panel provides the following options:

• Instance — Select a single instance to analyze. The Details screen requires exactly one instance to be selected. The screen will prompt you to select an instance if none is chosen.
• Database — Filter to a specific database on the selected instance
• Blocker ID — Filter to a specific blocking chain
• Application Host — Filter to blocking activity originating from a specific host machine

If no instance is selected, the screen displays a Select an Instance prompt. Use the Instance filter to choose one before the data loads. The selected instance name is displayed at the top of the screen once an instance is active.

Blocking Details

This table displays individual blocking event records for the selected instance. Each row represents a single occurrence of a blocking event at a point in time.

Columns:

Click any column header to sort ascending or descending.

Click the Lead Blocker field to open a pop-up displaying the full SQL statement text, which can be copied to clipboard.

Group By:

Use the Group By drop-down to change how events are aggregated. Click the expand arrow (›) on any row to drill into detail.

What It Tells You:

Events with high Blocking Impact and high victim counts represent the most damaging individual occurrences. Review the Start Time and End Time columns to understand duration. Long-running blockers often indicate open transactions that were not committed promptly, rather than an inherently expensive SQL statement.

Blocking Details Flyout

Click any row in the Blocking Details table to open the flyout panel for that event. The flyout provides a full breakdown of the blocking chain, including all sessions involved and their resource usage, wait statistics, and application context.

Properties

Displays summary information for the selected blocking event:

Lead Blocker

Displays the full SQL statement executed by the lead blocker for this event. Use the Copy button to copy the statement to clipboard, or the Full Screen button to view it in an expanded panel for easier reading.

Session Details

The lower section of the flyout is organized into three tabs, each showing data for every session involved in the blocking chain, including the lead blocker and all victims.

Resources

Wait Statistics

Application

What It Tells You:

The Resources tab helps identify sessions consuming disproportionate CPU, I/O, or memory in the chain. The Wait Statistics tab is the most direct path to understanding what each session is waiting on and which resource is the bottleneck. The Application tab identifies the application and host responsible for the lead blocker, which is useful when the blocking statement is generated by application code rather than a direct database operation.

Related Topics

• Blocking
• Blocking – Overview
• Instance Dashboard
• Alerts