dbt get_materialized_view_configuration_changes 简单说明

dbt 的get_materialized_view_configuration_changes 实际上是属于 on_configuration_change 相关的处理，目前一些实现主要是处理
物化视图的，以下说明下内部实现

内部处理

• 默认实现

dbt-adapter 中，实际为空

{% macro get_materialized_view_configuration_changes(existing_relation, new_config) %}

    /* {#

    It's recommended that configuration changes be formatted as follows:

    {"<change_category>": [{"action": "<name>", "context": ...}]}

 

    For example:

    {

        "indexes": [

            {"action": "drop", "context": "index_abc"},

            {"action": "create", "context": {"columns": ["column_1", "column_2"], "type": "hash", "unique": True}},

        ],

    }

 

    Either way, `get_materialized_view_configuration_changes` needs to align with `get_alter_materialized_view_as_sql`.

    #} */

    {{- log('Determining configuration changes on: ' ~ existing_relation) -}}

    {%- do return(adapter.dispatch('get_materialized_view_configuration_changes', 'dbt')(existing_relation, new_config)) -%}

{% endmacro %}

 

 

{% macro default__get_materialized_view_configuration_changes(existing_relation, new_config) %}

    {{ exceptions.raise_compiler_error("Materialized views have not been implemented for this adapter.") }}

{% endmacro %}

• pg 的实现

{% macro postgres__get_materialized_view_configuration_changes(existing_relation, new_config) %}

    {% set _existing_materialized_view = postgres__describe_materialized_view(existing_relation) %}

    # get_materialized_view_config_change_collection 实际是adapter 自己的实现，这个我以前简单说明过

    {% set _configuration_changes = existing_relation.get_materialized_view_config_change_collection(_existing_materialized_view, new_config.model) %}

    {% do return(_configuration_changes) %}

{% endmacro %}

pg adapter relation 处理(get_materialized_view_config_change_collection 方法)，此处返回的格式应该遵循上边的说明

def get_materialized_view_config_change_collection(

    self, relation_results: RelationResults, relation_config: RelationConfig

) -> Optional[PostgresMaterializedViewConfigChangeCollection]:

    config_change_collection = PostgresMaterializedViewConfigChangeCollection()

 

    existing_materialized_view = PostgresMaterializedViewConfig.from_relation_results(

        relation_results

    )

    new_materialized_view = PostgresMaterializedViewConfig.from_config(relation_config)

 

    config_change_collection.indexes = self._get_index_config_changes(

        existing_materialized_view.indexes, new_materialized_view.indexes

    )

 

    # we return `None` instead of an empty `PostgresMaterializedViewConfigChangeCollection` object

    # so that it's easier and more extensible to check in the materialization:

    # `core/../materializations/materialized_view.sql` :

    #     {% if configuration_changes is none %}

    if config_change_collection.has_changes:

        return config_change_collection

    return None

说明

dbt get_materialized_view_configuration_changes 的实现实际上是由具体的adapter 处理的，pg 是基于了自己扩展的relation

参考资料

https://docs.getdbt.com/reference/resource-configs/on_configuration_change