query-comment

dbt_project.yml

query-comment: string

The query-comment configuration also accepts a dictionary input, like so:

dbt_project.yml

models:
  my_dbt_project:
    +materialized: table

query-comment:
  comment: string
  append: true | false
  job-label: true | false  # BigQuery only

Definition

A string to inject as a comment in each query that dbt runs against your database. This comment can attribute SQL statements to specific dbt resources like models and tests.

The query-comment configuration can also call a macro that returns a string.

Default

By default, dbt will insert a JSON comment at the top of your query containing the information including the dbt version, profile and target names, and node ids for the resources it runs. For example:

/* {"app": "dbt", "dbt_version": "0.15.0rc2", "profile_name": "debug",
    "target_name": "dev", "node_id": "model.dbt2.my_model"} */

create view analytics.analytics.orders as (
    select ...
  );

Using the dictionary syntax

The dictionary syntax includes two keys:

• comment (optional, see above for default): The string to be injected into a query as a comment.
• append (optional, default=false): Whether a comment should be appended (added to the bottom of a query) or not (i.e. added to the top of a query). By default, comments are added to the top of queries (i.e. append: false).

This syntax is useful on databases like Snowflake which remove leading SQL comments.

Examples

Prepend a static comment

The following example injects a comment that reads /* executed by dbt */ into the header of the SQL queries that dbt runs.

dbt_project.yml

query-comment: "executed by dbt"

Example output:

/* executed by dbt */

select ...

Disable query comments

dbt_project.yml

query-comment:

Or:

dbt_project.yml

query-comment: null

Prepend a dynamic comment

The following example injects a comment that varies based on the configured user specified in the active dbt target.

dbt_project.yml

query-comment: "run by {{ target.user }} in dbt"

Example output:

/* run by drew in dbt */

select ...

Append the default comment

The following example uses the dictionary syntax to append (rather than prepend) the default comment.

Note that the comment: field is omitted to allow the default to be appended.

dbt_project.yml

query-comment:
  append: True

Example output:

select ...
/* {"app": "dbt", "dbt_version": "0.16.`0rc2`", "profile_name": "debug", "target_name": "dev", "node_id": "model.dbt2.my_model"} */
;

BigQuery: include query comment items as job labels

If query-comment.job-label is set to true, dbt will include the query comment items, if a dictionary, or the comment string, as job labels on the query it executes. These will be included in addition to labels specified in the BigQuery-specific config.

dbt_project.yml

query-comment:
  job-label: True

Append a custom comment

The following example uses the dictionary syntax to append (rather than prepend) a comment that varies based on the configured user specified in the active dbt target.

dbt_project.yml

query-comment:
  comment: "run by {{ target.user }} in dbt"
  append: True

Example output:

select ...
/* run by drew in dbt */
;

Intermediate: Use a macro to generate a comment

The query-comment config can reference macros in your dbt project. Simply create a macro with any name (query_comment is a good start!) in your macros directory, like so:

macros/query_comment.sql

{% macro query_comment() %}

  dbt {{ dbt_version }}: running {{ node.unique_id }} for target {{ target.name }}

{% endmacro %}

Then call the macro in your dbt_project.yml file. Make sure you quote the macro to avoid the YAML parser from trying to interpret the { as the start of a dictionary.

dbt_project.yml

query-comment: "{{ query_comment() }}"

Advanced: Use a macro to generate a comment

The following example shows a JSON query comment which can be parsed to understand the performance characteristics of your dbt project.

macros/query_comment.sql

{% macro query_comment(node) %}
    {%- set comment_dict = {} -%}
    {%- do comment_dict.update(
        app='dbt',
        dbt_version=dbt_version,
        profile_name=target.get('profile_name'),
        target_name=target.get('target_name'),
    ) -%}
    {%- if node is not none -%}
      {%- do comment_dict.update(
        file=node.original_file_path,
        node_id=node.unique_id,
        node_name=node.name,
        resource_type=node.resource_type,
        package_name=node.package_name,
        relation={
            "database": node.database,
            "schema": node.schema,
            "identifier": node.identifier
        }
      ) -%}
    {% else %}
      {%- do comment_dict.update(node_id='internal') -%}
    {%- endif -%}
    {% do return(tojson(comment_dict)) %}
{% endmacro %}

As above, call this macro as follows:

dbt_project.yml

query-comment: "{{ query_comment(node) }}"

Compilation context

The following context variables are available when generating a query comment:

Context Variable	Description
dbt_version	The version of dbt being used. For details about release versioning, refer to Versioning.
env_var	See env_var
modules	See modules
run_started_at	When the dbt invocation began
invocation_id	A unique ID for the dbt invocation
fromjson	See fromjson
tojson	See tojson
log	See log
var	See var
target	See target
connection_name	A string representing the internal name for the connection. This string is generated by dbt.
node	A dictionary representation of the parsed node object. Use node.unique_id, node.database, node.schema, and so on.

Note: The var() function in query-comment macros only accesses variables passed through the --vars argument in the CLI. Variables defined in the vars block of your dbt_project.yml are not accessible when generating query comments.