wardawgmalvicious Monitoring & diagnostics
Query Labels
SELECT ... FROM ...
OPTION (LABEL = 'PROJECT_Module_Description');
Labels appear in queryinsights.exec_requests_history.label. Use for tracking, filtering, and performance analysis.
Query Insights (30-day retention)
| View | Purpose |
|---|---|
queryinsights.exec_requests_history |
Every completed query: status, duration, CPU, data scanned |
queryinsights.exec_sessions_history |
Session history: login info, times |
queryinsights.long_running_queries |
Aggregated: median vs last-run time |
queryinsights.frequently_run_queries |
Run counts, execution times for recurring patterns |
Gotcha: Data appears with up to 15 minutes delay. After creating a new warehouse, views may return "Invalid object name" — wait ~2 minutes.
Top Expensive Queries
SELECT TOP 10
distributed_statement_id, query_hash, label,
total_elapsed_time_ms, allocated_cpu_time_ms,
data_scanned_remote_storage_mb, result_cache_hit
FROM queryinsights.exec_requests_history
ORDER BY allocated_cpu_time_ms DESC;
Aggregate by query_hash over the last 7 days to find recurring expensive patterns.
DMVs (Live State)
| DMV | Shows | Min Role |
|---|---|---|
sys.dm_exec_connections |
Active connections (session_id, client_address) | Admin only |
sys.dm_exec_sessions |
Authenticated sessions (login_name, login_time, status) | All roles (own sessions) |
sys.dm_exec_requests |
Active requests (command, start_time, total_elapsed_time) | All roles (own requests) |
-- Find long-running queries
SELECT request_id, session_id, command, start_time, total_elapsed_time, status
FROM sys.dm_exec_requests
WHERE status = 'running'
ORDER BY total_elapsed_time DESC;
-- Identify the user
SELECT login_name FROM sys.dm_exec_sessions WHERE session_id = <id>;
-- Kill a runaway query (Admin only)
KILL '<session_id>';
SQL Endpoint Metadata Sync (new sync — Preview, May 2026)
Diagnose slow/stale Lakehouse SQLEP reads when queries return data older than what has landed. On endpoints created under the new metadata-sync preview (opt-in, new endpoints only):
-- Inspect per-table sync freshness and blocked state
SELECT last_update_time_utc, latest_log_version, latest_checkpoint_version, is_blocked
FROM sys.dm_db_external_tables_log_status; -- is_blocked: 1 = last update blocked, 0 = succeeded
-- Force a targeted refresh of one table's data (data-only changes)
EXEC sys.sp_dw_refresh_ext_table 'dbo.<table>';
Schema changes (add/drop tables or columns, type changes) need the full-item Refresh SQL endpoint metadata REST API instead. Full preview note — enablement, architecture, limitations — lives in the fabric-spark skill; the slow-SQLEP gotcha cross-references it in the fabric-gotchas skill.
Result Set Caching (Preview)
result_cache_hit field in exec_requests_history: 1 = cache hit, 0 = miss, negative values = reason caching was skipped. Non-deterministic functions (GETDATE(), NEWID()) prevent caching. Cache auto-invalidates when underlying data changes.
Statistics
Auto-maintained for single-column histograms, average column length, and table cardinality. Manual CREATE STATISTICS / UPDATE STATISTICS available.
Gotcha: After a rolled-back transaction containing a large INSERT, auto-generated statistics can be inaccurate. Run UPDATE STATISTICS manually on affected columns to recover.
Reference
- Microsoft Learn: Monitor Fabric Data Warehouse (overview)
- Microsoft Learn: Query insights in Fabric Data Warehouse
- Microsoft Learn: Use query labels in Fabric Data Warehouse
- Comprehensive MS Learn link bundle (per-view T-SQL refs / DMVs / capacity throttling / workspace monitoring): references/REFERENCE.md
See also
- fabric-warehouse skill — T-SQL authoring rules for the queries you're monitoring
- fabric-gotchas skill — cross-cutting error index