dbt on_configuration_change 简单说明

dbt on_configuration_change 目前主要是在处理物化视图中，on_configuration_change 包含了三类设置

参考设置

• apply
  是默认参数，尝试进行更新存在的数据库对象
• continue
  允许继续运行，但是提供一个警告
• fail
  如果捕捉到变动就失败

参考使用

• 比如模型上的

{{ config(

    materialized="<materialization_name>",

    on_configuration_change="apply" | "continue" | "fail"

) }}

materialized_view 实现中的处理

{% macro materialized_view_get_build_sql(existing_relation, target_relation, backup_relation, intermediate_relation) %}

 

    {% set full_refresh_mode = should_full_refresh() %}

 

    -- determine the scenario we're in: create, full_refresh, alter, refresh data

    {% if existing_relation is none %}

        {% set build_sql = get_create_materialized_view_as_sql(target_relation, sql) %}

    {% elif full_refresh_mode or not existing_relation.is_materialized_view %}

        {% set build_sql = get_replace_sql(existing_relation, target_relation, sql) %}

    {% else %}

 

        -- get config options

        {% set on_configuration_change = config.get('on_configuration_change') %}

        {% set configuration_changes = get_materialized_view_configuration_changes(existing_relation, config) %}

 

        {% if configuration_changes is none %}

            {% set build_sql = refresh_materialized_view(target_relation) %}

 

        {% elif on_configuration_change == 'apply' %}

            {% set build_sql = get_alter_materialized_view_as_sql(target_relation, configuration_changes, sql, existing_relation, backup_relation, intermediate_relation) %}

        {% elif on_configuration_change == 'continue' %}

            {% set build_sql = '' %}

            {{ exceptions.warn("Configuration changes were identified and `on_configuration_change` was set to `continue` for `" ~ target_relation ~ "`") }}

        {% elif on_configuration_change == 'fail' %}

            {{ exceptions.raise_fail_fast_error("Configuration changes were identified and `on_configuration_change` was set to `fail` for `" ~ target_relation ~ "`") }}

 

        {% else %}

            -- this only happens if the user provides a value other than `apply`, 'skip', 'fail'

            {{ exceptions.raise_compiler_error("Unexpected configuration scenario") }}

 

        {% endif %}

 

    {% endif %}

 

    {% do return(build_sql) %}

 

{% endmacro %}

说明

模型变动是比较正常的事情，了解on_configuration_change 的一个使用以及配置是比较有用的

参考资料

dbt/include/global_project/macros/materializations/models/materialized_view.sql
https://docs.getdbt.com/reference/resource-configs/on_configuration_change