KQL is the language you use to query Azure Monitor Logs; Log Analytics is the Azure portal experience where you write, run, and inspect those queries. Together they help Azure operators investigate telemetry, troubleshoot issues, analyze patterns, and build inputs for alerts, dashboards, and reports. The data is near-real-time, not instantaneous: resource logs can take several minutes to appear.
What KQL and Log Analytics each do
Azure Monitor Logs stores and exposes log data for analysis. Kusto Query Language (KQL) is the language used to ask questions of that data. Log Analytics is the portal tool for authoring and running KQL queries and examining their results. A KQL query is a read-only request: it processes data and returns results rather than changing the underlying records. See Azure Monitor Logs overview and Log query overview.
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The phrase “real-time” needs qualification. Azure Monitor describes retrieval as near-real-time, and resource log data may take several minutes to become available. In its sample resource-log workflow, Microsoft advises expecting rows within about 10 minutes after generating sample data; that is tutorial guidance, not a guaranteed maximum or a service-wide latency commitment. Microsoft’s resource-log tutorial gives that example.
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Where you open Logs determines what data is in scope. Opening it from a workspace gives you workspace-level data; opening it from an individual resource limits the query to that resource context. If you are investigating activity across multiple resources, use Azure Monitor or a workspace-level query, provided you have permission to access the relevant data. The Log Analytics overview explains these entry points.
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Scope mistakes can look like missing telemetry. Before assuming a resource has no records, confirm the selected workspace or resource context and check that the data you want is routed there.
A practical KQL workflow for log diagnosis
- Select the workspace or resource context. Choose the scope that contains the telemetry you need, and confirm whether the investigation is limited to one resource or needs workspace-wide visibility.
- Find the table and inspect its schema. Start with a table relevant to the resource or log category. Microsoft recommends a table-first approach because it keeps the query clear and scoped. Its introductory example uses
SecurityEvent | take 10to inspect a small sample; the table and records will not necessarily exist in every workspace. Check the Azure Monitor data reference to map resource log categories to Log Analytics tables. - Set a time range and filter on known fields. Use
whereconditions to narrow the records to the period and values relevant to the incident. Check table and column spelling and case. When you know the column to search, a filter on that column is usually preferable to a broadsearchacross tables, which can be slower. - Keep only useful columns. Use projection to return fields needed to diagnose the issue, reducing noise in the result set.
- Aggregate when looking for patterns. Summarize counts or other relevant measures by time, resource, status, or another diagnostic dimension to make spikes and outliers easier to spot.
- Inspect, refine, and reuse. Review the returned rows, adjust the time range or filters, and refine the query until it answers the operational question. When appropriate, reuse it in an Azure Monitor workbook or as part of an alert workflow. The Get started with log queries guide walks through query basics.
Choose between KQL mode and Simple mode
Log Analytics offers both a KQL query experience and Simple mode, which supports point-and-click filtering and analysis. KQL gives direct control over the query; Simple mode can suit users who prefer interactive filtering over writing query expressions. The right choice depends on the task and the operator:
- Use KQL mode when you need precise filters, projections, or aggregations, or when you are comfortable editing query text.
- Use Simple mode when you are exploring data through point-and-click controls and do not need to compose KQL directly.
- Consider the next step. If the result will feed a workbook or alert, choose the approach that lets you create and maintain the needed analysis in Azure Monitor.
Microsoft describes both modes and their uses in the Log Analytics overview.
Why a query may return no rows—or fail
Data has not arrived yet
Resource logs may take several minutes to become queryable. If you have just enabled diagnostic logging or generated test activity, allow time for ingestion before treating an empty result as proof that the event did not occur. The tutorial’s approximately 10-minute expectation applies to its sample workflow, not every resource or situation.
The selected scope excludes the data
A resource-level Logs view is limited to that resource context. Switch to the workspace-level scope when the investigation requires other resources’ records and your access allows it.
The table or schema assumption is wrong
Resource log categories map to particular Log Analytics tables. Verify the table for the relevant resource and category in the Azure Monitor data reference, then check the table’s available columns before filtering.
Your account lacks query permissions
Microsoft lists Microsoft.OperationalInsights/workspaces/query/*/read as the required workspace query-read permission; Log Analytics Reader is an example role. If a query cannot run, confirm that your account has the necessary access for the workspace. The query guide describes the permission requirement.
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A query uses unsupported KQL features
Azure Monitor supports a subset of KQL, with differences from Azure Data Explorer. A statement, function, or operator that works in another Kusto-based service may not work in Azure Monitor; check the Azure Monitor log query overview before adapting a query.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Query API security requirement
Microsoft states that, since July 1, 2025, querying log data and events through the Log Analytics or Application Insights query API endpoints requires TLS 1.2 or higher. This requirement is specifically about those query API endpoints. Microsoft’s log query overview describes the requirement.
Learn with examples and references
Microsoft’s Log Analytics query documentation says it includes more than 500 curated example queries, with the collection continuing to grow. Examples can help you discover patterns to adapt, but check that the tables and columns they use are present in your own workspace. Start with Use queries in Log Analytics; the log query overview links to KQL tutorials and reference material.
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