Axiom Processing Language (APL)

APL is Axiom's query language for analyzing observability data. This skill provides comprehensive guidance for writing, debugging, and optimizing APL queries.

Quick Reference

Documentation: https://axiom.co/docs/apl/introduction

CLI usage: See references/cli.md

Core Workflow

1. List Available Datasets

axiom dataset list -f json

2. Discover Schema (CRITICAL - Always Do First)

['<dataset>'] | getschema

Never guess field names. The schema shows all fields with their types.

3. Sample Data

['<dataset>'] | limit 10

4. Write Query

See references for operators, functions, and patterns.

APL Syntax Essentials

Dataset Reference

['dataset-name']           // Bracket notation (required for names with dots/dashes)
dataset_name               // Plain identifier (only for simple names)

Field Reference

field_name                 // Plain field
['field.with.dots']        // Bracket notation for dotted fields
['service.name']           // OTel data (see references/otel.md for field mappings)

Basic Query Structure

['dataset']
| where <condition>
| extend <new_field> = <expression>
| summarize <aggregation> by <grouping>
| project <fields>
| sort by <field> desc
| limit 100

Time Handling

Always filter by time first - it's the most selective filter.

// Relative time
| where _time >= ago(1h)
| where _time >= ago(24h) and _time < ago(1h)

// Absolute time
| where _time >= datetime(2024-01-15T10:00:00Z)
| where _time between (datetime(2024-01-15) .. datetime(2024-01-16))

Time functions:

• ago(timespan) - Relative past time
• now() - Current time
• datetime(string) - Parse datetime
• bin(_time, 5m) - Time bucketing
• bin_auto(_time) - Automatic bucketing

When NOT to Use

• Simple field lookup: Use getschema directly instead of invoking the full skill
• Known query patterns: If you already have a working query, don't re-invoke for syntax help
• Real-time alerting: Use Axiom Monitors for continuous alerting, not ad-hoc queries

References

• CLI Usage - Command flags and execution
• Operators - Tabular and scalar operators
• Functions - String, datetime, aggregation functions
• Patterns - Query patterns by use case
• Common Gotchas - Mistakes and fixes
• OpenTelemetry - OTel field mappings and trace patterns