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

Check CLI usage (required):
```
mlflow traces search --help
```
Build filter query using syntax below
Execute search with appropriate flags
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

retrieving-mlflow-traces

NPX Install

Tags

SKILL.md Content

Retrieving MLflow Traces

Single Fetch vs Search

Trace Data Structure

Workflow

Prerequisite: Check CLI Usage

Searching Traces

By Run ID

By Session or User (Common for Debugging)

By Status

By Time Range

By Execution Time (Slow Traces)

By Tags and Metadata

By Assessment/Feedback

Full Text Search

Pagination

Output Options

Retrieving Single Trace

Filter Syntax

Python API