Azure Data Explorer & Kusto Query Language

Comprehensive skill for Azure Data Explorer (ADX) - Microsoft's fast, fully managed data analytics service for real-time analysis on large volumes of streaming data.

Quick Reference

Task	Go To
Write a KQL query	kql-query-language/
Ingest data into ADX	data-ingestion/
Create dashboards	visualization-dashboards/
Time series / ML	time-series-ml/
Manage tables / policies	management-commands/

KQL Essentials

Query Structure

TableName
| where TimeGenerated > ago(1h)
| where Level == "Error"
| summarize Count = count() by bin(TimeGenerated, 5m), Source
| order by TimeGenerated desc

Top 10 Operators

Operator	Purpose	Example
where	Filter rows	where Status == 200
project	Select columns	project Name, Age
extend	Add computed column	extend Duration = EndTime - StartTime
summarize	Aggregate	summarize count() by Category
join	Combine tables	join kind=inner OtherTable on Key
order by	Sort results	order by Timestamp desc
take	Limit rows	take 100
distinct	Unique values	distinct UserName
parse	Extract from string	parse Message with * "error:" ErrorMsg
mv-expand	Expand arrays	mv-expand Tags

Common Patterns

Time filtering:

| where TimeGenerated > ago(24h)
| where TimeGenerated between (datetime(2024-01-01) .. datetime(2024-01-31))

Aggregation:

| summarize
    Count = count(),
    AvgDuration = avg(Duration),
    P95 = percentile(Duration, 95)
  by bin(TimeGenerated, 1h)

String searching (prefer has over contains for performance):

| where Message has "error"        // Fast - word boundary match
| where Message contains "err"     // Slow - substring match

Join:

Table1
| join kind=leftouter (Table2) on CommonKey

Feature Areas

1. KQL Query Language

645+ functions and operators for data analysis.

Reference: feature-area-skill-resources/kql-query-language/reference.md

• Tabular operators (where, project, summarize, join, union, etc.)
• Scalar functions (string, datetime, math, conditional)
• Aggregation functions (count, sum, avg, dcount, percentile)
• Data types (string, datetime, dynamic, real, bool, etc.)

Best Practices: feature-area-skill-resources/kql-query-language/best-practices.md

• Query optimization techniques
• String operator performance (has vs contains)
• Join strategies and hints

Examples: feature-area-skill-resources/kql-query-language/examples.md

2. Data Ingestion

Multiple methods to get data into ADX.

Reference: feature-area-skill-resources/data-ingestion/reference.md

• Streaming ingestion (low latency, <4MB)
• Queued/batched ingestion (high throughput)
• Connectors: Event Hubs, Event Grid, IoT Hub, Kafka, Spark
• Ingestion mappings (CSV, JSON, Parquet, Avro)

Best Practices: feature-area-skill-resources/data-ingestion/best-practices.md

• Choosing streaming vs queued ingestion
• Batching policy tuning
• Error handling

Examples: feature-area-skill-resources/data-ingestion/examples.md

3. Visualization & Dashboards

Native dashboards and external integrations.

Reference: feature-area-skill-resources/visualization-dashboards/reference.md

• Native ADX dashboards
• render operator for inline visualization
• Power BI integration (DirectQuery, Import)
• Grafana integration

Best Practices: feature-area-skill-resources/visualization-dashboards/best-practices.md

• Dashboard design principles
• Chart type selection
• Performance optimization

Examples: feature-area-skill-resources/visualization-dashboards/examples.md

4. Time Series & Machine Learning

Advanced analytics for IoT, monitoring, and forecasting.

Reference: feature-area-skill-resources/time-series-ml/reference.md

• make-series operator
• Decomposition: series_decompose, series_decompose_anomalies
• Forecasting: series_decompose_forecast
• Python/R plugins for custom ML
• ONNX model inference

Best Practices: feature-area-skill-resources/time-series-ml/best-practices.md

• When to use time series analysis
• Anomaly detection tuning
• Native functions vs plugins

Examples: feature-area-skill-resources/time-series-ml/examples.md

5. Management Commands

297+ commands for schema, policies, and security.

Reference: feature-area-skill-resources/management-commands/reference.md

• Schema management (tables, columns, functions)
• 30+ policy types (retention, caching, partitioning, RLS)
• Materialized views
• Security roles and access control

Best Practices: feature-area-skill-resources/management-commands/best-practices.md

• Policy configuration patterns
• Schema design guidelines
• Access control best practices

Examples: feature-area-skill-resources/management-commands/examples.md

6. API & SDK Integration

Programmatic access via REST API and client SDKs.

Reference: feature-area-skill-resources/api-sdk-integration/reference.md

• REST API endpoints and authentication
• .NET, Python, Java, Node.js, Go SDKs
• Connection string formats

Best Practices: feature-area-skill-resources/api-sdk-integration/best-practices.md

Examples: feature-area-skill-resources/api-sdk-integration/examples.md

7. Security & Access Control

Authentication, authorization, and data protection.

Reference: feature-area-skill-resources/security-access-control/reference.md

• Microsoft Entra ID authentication
• RBAC roles and row-level security
• Network security and private endpoints
• Customer-managed keys (CMK)

Best Practices: feature-area-skill-resources/security-access-control/best-practices.md

Examples: feature-area-skill-resources/security-access-control/examples.md

8. Cluster Management

Cluster operations, scaling, and monitoring.

Reference: feature-area-skill-resources/cluster-management/reference.md

• SKU selection and sizing
• Auto-scale configuration
• Monitoring and diagnostics

Best Practices: feature-area-skill-resources/cluster-management/best-practices.md

Examples: feature-area-skill-resources/cluster-management/examples.md

9. Business Continuity

High availability and disaster recovery.

Reference: feature-area-skill-resources/business-continuity/reference.md

• Follower databases
• Cross-region replication
• Backup and restore

Best Practices: feature-area-skill-resources/business-continuity/best-practices.md

Examples: feature-area-skill-resources/business-continuity/examples.md

10. Integration Services

Azure service integrations.

Reference: feature-area-skill-resources/integration-services/reference.md

• Azure Monitor, Synapse, Data Factory
• Logic Apps, Power Automate
• Cross-product queries

Best Practices: feature-area-skill-resources/integration-services/best-practices.md

Examples: feature-area-skill-resources/integration-services/examples.md

11. UDF Functions Library

Pre-built user-defined functions for advanced analytics.

Reference: feature-area-skill-resources/udf-functions-library/reference.md

• Statistical tests (t-test, KS test, normality)
• ML functions (K-means, DBSCAN)
• Time series and text analytics UDFs

Best Practices: feature-area-skill-resources/udf-functions-library/best-practices.md

Examples: feature-area-skill-resources/udf-functions-library/examples.md

12. Tools & Clients

Desktop, CLI, and web tools.

Reference: feature-area-skill-resources/tools-clients/reference.md

• Kusto.Explorer (desktop IDE)
• Kusto.Cli (command line)
• Web UI and Emulator

Best Practices: feature-area-skill-resources/tools-clients/best-practices.md

Examples: feature-area-skill-resources/tools-clients/examples.md

Resources

Official Documentation

The complete Microsoft documentation is available as a submodule at: submodules/dataexplorer-docs/

Investigation Reports

Detailed analysis from the skill creation process:

• investigation-reports/repository-layout/ - Repo structure analysis
• investigation-reports/feature-overview/ - Feature taxonomy and mapping
• investigation-reports/feature-in-depth/ - Comprehensive research per feature

See Also

• Azure Data Explorer Documentation
• KQL Quick Reference
• KQL Cheat Sheet