TempDB is a shared system resource used by every database on a SQL Server instance for sorting, hashing, temporary tables, table variables, spool operators, row versioning, and index rebuild operations. Because it's shared, a single poorly-written or poorly-optimized query can consume disproportionate tempdb space and degrade performance for every other workload on the instance — not just its own.
TempDB problems rarely stay isolated to the query that caused them — they become instance-level availability and performance incidents. Monitoring at the query level turns an unpredictable, hard-to-diagnose outage risk into an early warning with root cause.
The following DPA alert definition finds queries consuming more than 30-50MB of TempDB space (thresholds) as a warning and queries consuming more than 50MB as critical. This gives you immediate visibility into which specific queries are driving TempDB growth — without needing to manually query the DMVs during an incident.
