Search Runs

The MLflow UI and API support searching runs within a single experiment or a group of experiments using a search filter API. This API is a simplified version of the SQL WHERE clause.


A search filter is one or more expressions joined by the AND keyword. The syntax does not support OR. Each expression has three parts: an identifier on the left-hand side (LHS), a comparator, and constant on the right-hand side (RHS).

Example Expressions

  • Search for the subset of runs with logged accuracy metric greater than 0.92.

    metrics.accuracy > 0.92
  • Search for runs created using a Logistic Regression model, a learning rate (lambda) of 0.001, and recorded error metric under 0.05.

    params.model = "LogisticRegression" and params.lambda = "0.001" and metrics.error <= 0.05
  • Search for all failed runs.

    attributes.status = "FAILED"


Required in the LHS of a search expression. Signifies an entity to compare against.

An identifier has two parts separated by a period: the type of the entity and the name of the entity. The type of the entity is metrics, params, attributes, or tags. The entity name can contain alphanumeric characters and special characters.

This section describes supported entity names and how to specify such names in search expressions.

Entity Names Containing Special Characters

When a metric, parameter, or tag name contains a special character like hyphen, space, period, and so on, enclose the entity name in double quotes or backticks.


metrics.`error rate`

Entity Names Starting with a Number

Unlike SQL syntax for column names, MLflow allows logging metrics, parameters, and tags names that have a leading number. If an entity name contains a leading number, enclose the entity name in double quotes. For example:

metrics."2019-04-02 error rate"

Run Attributes

You can search using the following run attributes contained in mlflow.entities.RunInfo: run_id, run_name, status, artifact_uri, user_id, start_time and end_time. The run_id, run_name, status, user_id and artifact_uri attributes have string values, while start_time and end_time are numeric. Other fields in mlflow.entities.RunInfo are not searchable.


  • The experiment ID is implicitly selected by the search API.

  • A run’s lifecycle_stage attribute is not allowed because it is already encoded as a part of the API’s run_view_type field. To search for runs using run_id, it is more efficient to use get_run APIs.


attributes.artifact_uri = 'models:/mymodel/1'
attributes.status = 'ACTIVE'
# RHS value for start_time and end_time are unix timestamp
attributes.start_time >= 1664067852747
attributes.end_time < 1664067852747
attributes.user_id = 'user1'
attributes.run_name = 'my-run'
attributes.run_id = 'a1b2c3d4'
attributes.run_id IN ('a1b2c3d4', 'e5f6g7h8')

MLflow Tags

You can search for MLflow tags by enclosing the tag name in double quotes or backticks. For example, to search by owner of an MLflow run, specify tags."mlflow.user" or tags.`mlflow.user`.




There are two classes of comparators: numeric and string.

  • Numeric comparators (metrics): =, !=, >, >=, <, and <=.

  • String comparators (params, tags, and attributes): =, !=, LIKE and ILIKE.


The search syntax requires the RHS of the expression to be a constant. The type of the constant depends on LHS.

  • If LHS is a metric, the RHS must be an integer or float number.

  • If LHS is a parameter or tag, the RHS must be a string constant enclosed in single or double quotes.

Programmatically Searching Runs

The MLflow UI supports searching runs contained within the current experiment. To search runs across multiple experiments, use one of the client APIs.


Use the MlflowClient.search_runs() or mlflow.search_runs() API to search programmatically. You can specify the list of columns to order by (for example, “metrics.rmse”) in the order_by column. The column can contain an optional DESC or ASC value; the default is ASC. The default ordering is to sort by start_time DESC, then run_id.

The mlflow.search_runs() API can be used to search for runs within specific experiments which can be identified by experiment IDs or experiment names, but not both at the same time.


Using both experiment_ids and experiment_names in the same call will result in error unless one of them is None or []

For example, if you’d like to identify the best active run from experiment ID 0 by accuracy, use:

from mlflow import MlflowClient
from mlflow.entities import ViewType

run = MlflowClient().search_runs(
  order_by=["metrics.accuracy DESC"]

To get all active runs from experiments IDs 3, 4, and 17 that used a CNN model with 10 layers and had a prediction accuracy of 94.5% or higher, use:

from mlflow import MlflowClient
from mlflow.entities import ViewType

query = "params.model = 'CNN' and params.layers = '10' and metrics.`prediction accuracy` >= 0.945"
runs = MlflowClient().search_runs(experiment_ids=["3", "4", "17"], filter_string=query, run_view_type=ViewType.ACTIVE_ONLY)

To search all known experiments for any MLflow runs created using the Inception model architecture:

from mlflow import MlflowClient
from mlflow.entities import ViewType

all_experiments = [exp.experiment_id for exp in MlflowClient().list_experiments()]
runs = MlflowClient().search_runs(experiment_ids=all_experiments, filter_string="params.model = 'Inception'", run_view_type=ViewType.ALL)

To get all runs from the experiment named “Social NLP Experiments”, use:

import mlflow

runs = mlflow.search_runs(experiment_names=["Social NLP Experiments"])


The R API is similar to the Python API.

  filter = "metrics.rmse < 0.9 and tags.production = 'true'",
  experiment_ids = as.character(1:2),
  order_by = " DESC"


The Java API is similar to Python API.

List<Long> experimentIds = Arrays.asList("1", "2", "4", "8");
List<RunInfo> searchResult = client.searchRuns(experimentIds, "metrics.accuracy_score < 99.90");