# Retrieving Mlflow Traces

> Retrieves MLflow traces using CLI or Python API. Use when the user asks to get a trace by ID, find traces, filter traces by status/tags/metadata/execution time, query traces, or debug failed traces. Triggers on "get trace", "search traces", "find failed traces", "filter traces by", "traces slower than", "query MLflow traces". Use when this capability is needed.

- Skill: `tomevault-io/retrieving-mlflow-traces` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add tomevault-io/retrieving-mlflow-traces`
- Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/retrieving-mlflow-traces/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Integrations & APIs
- Author: tomevault-io (https://skillmd.com/u/tomevault-io)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/tomevault-io/retrieving-mlflow-traces

---


# Retrieving MLflow Traces

## Single Fetch vs Search

Choose the right approach based on what you have:

| You have... | Use | Command |
|-------------|-----|---------|
| **Trace ID** | Single fetch | `mlflow traces get --trace-id <id>` |
| **Session/user/filters** | Search | `mlflow traces search --experiment-id <id> --filter-string "..."` |

**Single fetch** - Use when you have a specific trace ID (e.g., from UI, logs, or API response):
```bash
mlflow traces get --trace-id tr-69f72a3772570019f2f91b75b8b5ded9
```

**Search** - Use when you need to find traces by criteria (session, user, status, time range, etc.):
```bash
mlflow traces search --experiment-id 1 --filter-string "metadata.\`mlflow.trace.session\` = 'session_abc'"
```

---

## Trace Data Structure

- **TraceInfo**: `trace_id`, `status` (OK/ERROR), `timestamp_ms`, `execution_time_ms`, `tags`, `metadata`, `assessments` (human feedback, evaluation results)
- **Spans**: Tree of operations with `name`, `type`, `attributes`, `start_time`, `end_time`

## Workflow

1. **Check CLI usage** (required): `mlflow traces search --help`
2. **Build filter query** using syntax below
3. **Execute search** with appropriate flags
4. **Retrieve details** for specific traces if needed

## Prerequisite: Check CLI Usage

```bash
mlflow traces search --help
```

Always run this first to get accurate flags for the installed MLflow version.

## Searching Traces

The `mlflow traces search` command is used to search for traces in an MLflow experiment.

### By Run ID

Filter traces associated with a specific MLflow run:

```bash
# All traces for a run
mlflow traces search --run-id <run_id>

# Failed traces for a run
mlflow traces search --run-id <run_id> --filter-string "trace.status = 'ERROR'"

# Can combine with experiment-id
mlflow traces search --experiment-id 1 --run-id <run_id>
```

### By Session or User (Common for Debugging)

When debugging an issue from the MLflow UI, filter by session or user ID to get all related traces:

```bash
# All traces for a specific session (use backticks for special characters in key)
mlflow traces search --experiment-id 1 --filter-string "metadata.\`mlflow.trace.session\` = 'session_abc123'"

# All traces for a specific user
mlflow traces search --experiment-id 1 --filter-string "metadata.\`mlflow.trace.user\` = 'user_456'"

# Failed traces in a session (for root cause analysis)
mlflow traces search --experiment-id 1 --filter-string "metadata.\`mlflow.trace.session\` = 'session_abc123' AND trace.status = 'ERROR'"

# Session traces ordered by time (to see sequence of events)
mlflow traces search --experiment-id 1 --filter-string "metadata.\`mlflow.trace.session\` = 'session_abc123'" --order-by "timestamp_ms ASC"
```

### By Status

```bash
mlflow traces search --experiment-id 1 --filter-string "trace.status = 'ERROR'"
mlflow traces search --experiment-id 1 --filter-string "trace.status = 'OK'"
```

### By Time Range

```bash
# Timestamps are in milliseconds since epoch
# Get current time in ms: $(date +%s)000
# Last hour: $(( $(date +%s)000 - 3600000 ))

mlflow traces search --experiment-id 1 --filter-string "trace.timestamp_ms > $(( $(date +%s)000 - 3600000 ))"
```

### By Execution Time (Slow Traces)

```bash
# Traces slower than 1 second
mlflow traces search --experiment-id 1 --filter-string "trace.execution_time_ms > 1000"
```

### By Tags and Metadata

```bash
# By tag
mlflow traces search --experiment-id 1 --filter-string "tag.environment = 'production'"

# By metadata
mlflow traces search --experiment-id 1 --filter-string "metadata.user_id = 'user_123'"

# Escape special characters in key names with backticks
mlflow traces search --experiment-id 1 --filter-string "tag.\`model-name\` = 'gpt-4'"
mlflow traces search --experiment-id 1 --filter-string "metadata.\`user.id\` = 'abc'"
```

### By Assessment/Feedback

```bash
mlflow traces search --experiment-id 1 --filter-string "feedback.rating = 'positive'"
```

### Full Text Search

```bash
mlflow traces search --experiment-id 1 --filter-string "trace.text LIKE '%error%'"
```

### Pagination

Control result count and iterate through pages:

```bash
# Limit results per page
mlflow traces search --experiment-id 1 --max-results 50

# Output includes "Next page token: <token>" if more results exist
# Use --page-token to fetch next page
mlflow traces search --experiment-id 1 --max-results 50 --page-token "eyJvZmZzZXQiOiA1MH0="
```

### Output Options

```bash
# Output format (table or json)
mlflow traces search --experiment-id 1 --output json

# Include span details in output
mlflow traces search --experiment-id 1 --include-spans

# Order results
mlflow traces search --experiment-id 1 --order-by "timestamp_ms DESC"
```

## Retrieving Single Trace

When you need to retrieve details about a specific trace, use the `mlflow traces get` command.

```bash
mlflow traces get --trace-id <trace_id>
```

## Filter Syntax

For detailed syntax, fetch from documentation:
```
WebFetch(
  url: "https://mlflow.org/docs/latest/genai/tracing/search-traces.md",
  prompt: "Extract the filter syntax table showing supported fields, operators, and examples."
)
```

**Common filters:**
- `trace.status`: OK, ERROR, IN_PROGRESS
- `trace.execution_time_ms`, `trace.timestamp_ms`: numeric comparison
- `metadata.\`mlflow.trace.session\``, `metadata.\`mlflow.trace.user\``: session/user filtering
- `tag.<key>`, `metadata.<key>`: exact match or pattern
- `span.name`, `span.type`: exact match or pattern
- `feedback.<name>`, `expectation.<name>`: assessments

**Pattern operators:** `LIKE`, `ILIKE` (case-insensitive), `RLIKE` (regex)

## Python API

For `mlflow.search_traces()`, see: https://mlflow.org/docs/latest/genai/tracing/search-traces.md

---
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<!-- tomevault:4.0:skill_md:2026-04-11 -->