fabric-warehouse-monitoring

# Monitoring & diagnostics ## Query Labels ```sql 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 ```sql 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) | ```sql -- 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): ```sql -- 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)](https://learn.microsoft.com/fabric/data-warehouse/monitoring-overview) - Microsoft Learn: [Query insights in Fabric Data Warehouse](https://learn.microsoft.com/fabric/data-warehouse/query-insights) - Microsoft Learn: [Use query labels in Fabric Data Warehouse](https://learn.microsoft.com/fabric/data-warehouse/query-label) - Comprehensive MS Learn link bundle (per-view T-SQL refs / DMVs / capacity throttling / workspace monitoring): [references/REFERENCE.md](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