Locks
The Lock band shows locks acquired and released over the life of the query - how SQL Server protects data being read and modified from conflicting changes by other transactions. Locks are only captured when enabled - see the Events menu.
Locks are bucketed per object, and each object's locks are banded by category, split into non-schema and schema locks - schema locks are banded separately so they don't dominate the view, since they are typically held for longer and across a broader scope than row/page/key locks.
Within a band, locks are drawn as a histogram - a bar chart showing the volume of locks held in that category over time.
Categories and colours
The lock modes are grouped into categories:
| Category | Lock modes | Colour |
|---|---|---|
| Read | S, IS | Green |
| Update | U, IU, SIU | Amber |
| Write / Exclusive | X, IX, SIX, UIX | Red |
| Schema | SCH_S, SCH_M | Purple |
| Range | RS_, RI_, RX_* | Blue |
| Bulk | BU | Teal |
These colours are used consistently wherever lock state is shown - including the border drawn around pages on the Allocations pane. Intent lock modes (the I-prefixed and SI/UI modes) are dimmed relative to their full counterpart.
Lock escalation
When a query holds too many fine-grained locks, SQL Server escalates them to a single coarser lock on the whole object. A lock escalation is marked as a discrete event on the timeline - a solid vertical line at the point of escalation, with a tooltip describing the change, e.g. "Lock escalation: X (Exclusive) on Object, replacing 6249 lock(s)":
