Log Query Examples

Platform-specific log query examples for troubleshooting and analysis

Available in: v2.5.0+ View Log Aggregation Setup →

Overview

This guide provides platform-specific query examples for common log analysis tasks across all 6 supported platforms.

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AWS CloudWatch Insights

Query Language

CloudWatch Insights uses a SQL-like query language with piped commands.

Common Queries

Find All Errors

fields @timestamp, level, message, trace_id, user_id
| filter level = "ERROR"
| sort @timestamp desc
| limit 100

Errors by User

fields @timestamp, message, user_id, trace_id
| filter level = "ERROR"
| stats count() by user_id
| sort count desc

Trace-Specific Logs

fields @timestamp, level, message, span_id
| filter trace_id = "0af7651916cd43dd8448eb211c80319c"
| sort @timestamp asc

Slow Requests (Performance)

fields @timestamp, message, duration_ms
| filter message like /request completed/
| filter duration_ms > 1000
| sort duration_ms desc

Error Rate Over Time

fields @timestamp, level
| filter level = "ERROR"
| stats count() as error_count by bin(5m)

Top Error Messages

fields message
| filter level = "ERROR"
| stats count() as occurrence by message
| sort occurrence desc
| limit 10

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GCP Log Explorer

Query Language

GCP uses a custom query language with filters and boolean logic.

Common Queries

Find All Errors

resource.type="k8s_container"
logName="projects/YOUR_PROJECT/logs/mcp-server-langgraph"
severity="ERROR"

Trace-Specific Logs

resource.type="k8s_container"
jsonPayload.trace_id="0af7651916cd43dd8448eb211c80319c"

Errors in Last Hour

resource.type="k8s_container"
severity="ERROR"
timestamp>="2025-10-15T13:00:00Z"

Search by User ID

resource.type="k8s_container"
jsonPayload.user_id="alice"

Authentication Failures

resource.type="k8s_container"
jsonPayload.message=~"authentication failed"
severity="WARNING" OR severity="ERROR"

High Memory Usage

resource.type="k8s_container"
jsonPayload.message=~"memory.*exceeded"

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Azure Monitor (KQL)

Query Language

Azure uses Kusto Query Language (KQL), a powerful query language similar to SQL.

Common Queries

Find All Errors

traces
| where severityLevel >= 3  // ERROR level
| project timestamp, message, customDimensions.trace_id, customDimensions.user_id
| order by timestamp desc
| take 100

Errors by Service

traces
| where severityLevel >= 3
| summarize count() by tostring(customDimensions.service)
| order by count_ desc

Trace-Specific Logs

traces
| where customDimensions.trace_id == "0af7651916cd43dd8448eb211c80319c"
| project timestamp, severityLevel, message
| order by timestamp asc

Request Duration Analysis

traces
| where message contains "request completed"
| extend duration_ms = todouble(customDimensions.duration_ms)
| summarize avg(duration_ms), percentile(duration_ms, 95), percentile(duration_ms, 99) by bin(timestamp, 5m)
| render timechart

User Activity Timeline

traces
| where customDimensions.user_id == "alice"
| project timestamp, message, customDimensions.action
| order by timestamp desc

Error Rate Trend

traces
| summarize
    total = count(),
    errors = countif(severityLevel >= 3)
    by bin(timestamp, 5m)
| extend error_rate = (errors * 100.0) / total
| render timechart

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Elasticsearch (Kibana)

Query Language

Elasticsearch uses Query DSL (JSON-based) or KQL in Kibana.

Common Queries

Find All Errors (Query DSL)

{
  "query": {
    "bool": {
      "must": [
        { "match": { "level": "ERROR" } }
      ]
    }
  },
  "sort": [
    { "timestamp": { "order": "desc" } }
  ],
  "size": 100
}

Trace-Specific Logs

{
  "query": {
    "term": {
      "trace_id.keyword": "0af7651916cd43dd8448eb211c80319c"
    }
  },
  "sort": [
    { "timestamp": { "order": "asc" } }
  ]
}

Time Range + Level Filter

{
  "query": {
    "bool": {
      "must": [
        {
          "range": {
            "timestamp": {
              "gte": "now-1h",
              "lte": "now"
            }
          }
        },
        { "match": { "level": "ERROR" } }
      ]
    }
  }
}

Aggregation: Errors by User

{
  "size": 0,
  "query": {
    "match": { "level": "ERROR" }
  },
  "aggs": {
    "errors_by_user": {
      "terms": {
        "field": "user_id.keyword",
        "size": 10
      }
    }
  }
}

Kibana KQL (Discover Tab)

level: "ERROR" AND timestamp > now-1h

trace_id: "0af7651916cd43dd8448eb211c80319c"

message: “authentication failed” AND user_id: “alice”

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## Datadog

### Query Language

Datadog uses a custom query syntax with filters and facets.

### Common Queries

#### Find All Errors
```yaml
status:error

Trace-Specific Logs

@trace_id:0af7651916cd43dd8448eb211c80319c

Errors by Service

status:error service:mcp-server-langgraph

User-Specific Logs

@user_id:alice

Time Range + Error Filter

status:error @timestamp:[now-1h TO now]

Authentication Failures

@message:"authentication failed" (status:error OR status:warn)

High Latency Requests

@duration_ms:>1000 @message:"request completed"

Errors with Stack Traces

status:error @exception.stacktrace:*

Datadog Analytics

Error Count by User

status:error | count by @user_id

P95 Request Duration

@message:"request completed" | p95(@duration_ms) by @http.route

Error Rate Over Time

status:error | timeseries count()

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Splunk (SPL)

Query Language

Splunk uses Search Processing Language (SPL).

Common Queries

Find All Errors

index=main source="mcp-server-langgraph" level="ERROR"
| table _time, message, trace_id, user_id
| sort -_time
| head 100

Trace-Specific Logs

index=main source="mcp-server-langgraph" trace_id="0af7651916cd43dd8448eb211c80319c"
| sort _time

Errors by User

index=main source="mcp-server-langgraph" level="ERROR"
| stats count by user_id
| sort -count

Time Range + Level Filter

index=main source="mcp-server-langgraph" earliest=-1h level="ERROR"
| table _time, message, user_id

Error Rate Over Time

index=main source="mcp-server-langgraph"
| timechart span=5m count(eval(level="ERROR")) as errors, count as total
| eval error_rate=(errors/total)*100

Top Error Messages

index=main source="mcp-server-langgraph" level="ERROR"
| stats count by message
| sort -count
| head 10

Request Duration Statistics

index=main source="mcp-server-langgraph" message="request completed"
| stats avg(duration_ms) as avg_duration, p95(duration_ms) as p95_duration, max(duration_ms) as max_duration by http_route
| sort -p95_duration

User Activity Timeline

index=main source="mcp-server-langgraph" user_id="alice"
| table _time, message, action
| sort _time

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Common Use Cases

1. Distributed Tracing

Find all logs for a specific request (across all platforms):

CloudWatch

fields @timestamp, level, message, span_id
| filter trace_id = "YOUR_TRACE_ID"
| sort @timestamp asc

2. Error Investigation

Find errors and group by type:

CloudWatch

fields @timestamp, message
| filter level = "ERROR"
| stats count() by message
| sort count desc

3. Performance Analysis

Find slow requests (>1s):

CloudWatch

fields @timestamp, http_route, duration_ms
| filter duration_ms > 1000
| sort duration_ms desc

4. Security Monitoring

Detect authentication failures:

CloudWatch

fields @timestamp, user_id, ip_address, message
| filter message like /authentication failed/
| sort @timestamp desc

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Advanced Queries

Multi-Field Correlation

Find errors for specific user in specific time range:

CloudWatch

fields @timestamp, level, message, trace_id
| filter user_id = "alice"
| filter level = "ERROR"
| filter @timestamp >= 1697385600000
| filter @timestamp <= 1697472000000
| sort @timestamp desc

Azure (KQL)

traces
| where customDimensions.user_id == "alice"
| where severityLevel >= 3
| where timestamp between(datetime(2025-10-15T00:00:00) .. datetime(2025-10-16T00:00:00))
| project timestamp, message, customDimensions.trace_id

Datadog

@user_id:alice status:error @timestamp:[2025-10-15T00:00:00 TO 2025-10-16T00:00:00]

Statistical Analysis

Calculate P95, P99 latency:

CloudWatch

fields duration_ms
| filter message like /request completed/
| stats avg(duration_ms) as avg, pct(duration_ms, 95) as p95, pct(duration_ms, 99) as p99

Azure (KQL)

traces
| where message contains "request completed"
| extend duration = todouble(customDimensions.duration_ms)
| summarize
    avg(duration),
    percentile(duration, 95),
    percentile(duration, 99)

Splunk

message="request completed"
| stats avg(duration_ms) as avg, p95(duration_ms) as p95, p99(duration_ms) as p99

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Best Practices

1. Use Structured Fields

Always query on structured fields (not text search on message):

- ✅ user_id = "alice"
❌ message like /user alice/

2. Limit Time Ranges

Always specify time ranges for better performance:

- ✅ timestamp:[now-1h TO now]
❌ No time filter (searches all data)

3. Use Trace IDs

For request debugging, always use trace_id:

- ✅ trace_id = "0af7651916cd43dd..."
❌ Searching multiple unrelated fields

4. Aggregate When Possible

Use aggregations instead of returning all results:

- ✅ stats count() by user_id
❌ return 10000 individual log entries

5. Index Patterns

Ensure proper index patterns for fast queries:

• Elasticsearch: Use index templates
• Splunk: Configure index-time field extraction
• Datadog: Define facets for frequently queried fields

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Troubleshooting Queries

No Results Found

1. Check time range - Logs might be outside selected window
2. Verify field names - Use autocomplete or schema browser
3. Check index/source - Ensure querying correct data source
4. Validate syntax - Platform-specific syntax varies

Slow Queries

1. Add time range - Limit data scanned
2. Use indexed fields - Query on indexed fields only
3. Avoid wildcards - Especially leading wildcards (*error)
4. Reduce result size - Use | head or | limit

Missing Fields

1. Check JSON structure - Use fields @message to see all fields
2. Verify field mapping - Fields must be extracted/mapped correctly
3. Check log format - Ensure JSON logging is enabled (LOG_FORMAT=json)

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Next Steps

• Log Aggregation Setup - Platform-specific setup guides
• Observability Guide - Complete observability setup
• Troubleshooting - Common issues and solutions