ClickHouse/doc/reference/en/settings/settings_profiles.rst

Settings profiles
=================
A settings profile is a collection of settings grouped under the same name. Each ClickHouse user has a profile.
To apply all the settings in a profile, set 'profile'. Example:
.. code-block:: sql

  SET profile = 'web'
  
Load the 'web' profile. That is, set all the options belonging to the 'web' profile.

Settings profiles are declared in the user config file. This is normally 'users.xml'.

Example:

.. code-block:: xml

  <!-- Settings profiles. -->
  <profiles>
      <!-- Default settings -->
      <default>
          <!-- Maximum number of threads for executing a single query. -->
          <max_threads>8</max_threads>
      </default>
      <!-- Settings for queries from the user interface -->
      <web>
          <max_rows_to_read>1000000000</max_rows_to_read>
          <max_bytes_to_read>100000000000</max_bytes_to_read>
          <max_rows_to_group_by>1000000</max_rows_to_group_by>
          <group_by_overflow_mode>any</group_by_overflow_mode>
          <max_rows_to_sort>1000000</max_rows_to_sort>
          <max_bytes_to_sort>1000000000</max_bytes_to_sort>
          <max_result_rows>100000</max_result_rows>
          <max_result_bytes>100000000</max_result_bytes>
          <result_overflow_mode>break</result_overflow_mode>
          <max_execution_time>600</max_execution_time>
          <min_execution_speed>1000000</min_execution_speed>
          <timeout_before_checking_execution_speed>15</timeout_before_checking_execution_speed>
          <max_columns_to_read>25</max_columns_to_read>
          <max_temporary_columns>100</max_temporary_columns>
          <max_temporary_non_const_columns>50</max_temporary_non_const_columns>
          <max_subquery_depth>2</max_subquery_depth>
          <max_pipeline_depth>25</max_pipeline_depth>
          <max_ast_depth>50</max_ast_depth>
          <max_ast_elements>100</max_ast_elements>
          <readonly>1</readonly>
      </web>
  </profiles>


In the example, two profiles are set: ``default`` and ``web``. The ``default`` profile has a special purpose - it must always be present and is applied when starting the server. In other words, the ``default`` profile contains default settings. The ``web`` profile is a regular profile that can be set using the SET query or using a URL parameter in an HTTP query.

Settings profiles can inherit from each other. To use inheritance, indicate the 'profile' setting before the other settings that are listed in the profile.