adding fct_unused_staging_models

docs/rules.md

@@ -19,6 +19,7 @@ hide:
 |Modeling                                      |[Root Models](../rules/modeling/#root-models)                                                                          |`fct_root_models`|
 |Modeling                                      |[Staging Models Dependent on Downstream Models](../rules/modeling/#staging-models-dependent-on-downstream-models)      |`fct_staging_dependent_on_marts_or_intermediate`|
 |Modeling                                      |[Unused Sources](../rules/modeling/#unused-sources)                                                                    |`fct_unused_sources`|
+|Modeling                                      |[Unused Staging Models](../rules/modeling/#unused-staging-models)                                                      |`fct_unused_staging_models`|
 |Modeling                                      |[Models with Too Many Joins](../rules/modeling/#models-with-too-many-joins)                                            |`fct_too_many_joins`|
 |Testing                                       |[Missing Primary Key Tests](../rules/testing/#missing-primary-key-tests)                                               |`fct_missing_primary_key_tests`|
 |Testing                                       |[Missing Source Freshness](../rules/testing/#missing-source-freshness)                                                 |`fct_sources_without_freshness`|

docs/rules/modeling.md

@@ -430,6 +430,26 @@ or any other nested information.
 
 ![A refactored DAG showing three sources which are each being referenced by an accompanying staging model](https://user-images.githubusercontent.com/30663534/159603703-6e94b00b-07d1-4f47-89df-8e5685d9fcf0.png){ width=500 }
 
+---
+## Unused Staging Models
+
+`fct_unused_staging_models` ([source](https://github.com/dbt-labs/dbt-project-evaluator/tree/main/models/marts/dag/fct_unused_staging_models.sql)) shows each staging model with 0 children.
+
+**Example**
+
+`model.stg_auditboard__teams` isn't being referenced.
+
+![A DAG showing three staging_models which are each being referenced by an accompanying staging model, and one source that isn't being referenced at all](../img/unused_staging_models.png){ width=500 }
+
+**Reason to Flag**
+
+This represents a staging models that was created but never used in downstream models. This simply 
+represents the buildup of cruft in the project that doesn’t need to be there.
+
+**How to Remediate**
+
+Remove the unused staging model and their sources from the project.
+
 ---
 
 ## Models with Too Many Joins

integration_tests/seeds/dag/dag_seeds.yml

@@ -42,6 +42,12 @@ seeds:
           name: equality_fct_unused_sources
           compare_model: ref('fct_unused_sources')
 
+  - name: test_fct_unused_staging_models
+    data_tests:
+      - dbt_utils.equality:
+          name: equality_fct_unused_staging_models
+          compare_model: ref('fct_unused_staging_models')
+
   - name: test_fct_source_fanout
     data_tests:
       - dbt_utils.equality:

integration_tests/seeds/dag/test_fct_unused_staging_models.csv

@@ -0,0 +1,3 @@
+parent
+model.stage_model_4
+model.stage_model_5

models/marts/dag/dag.yml

@@ -48,6 +48,10 @@ models:
     description: "This table shows each source with 0 children."
     data_tests:
       - is_empty
+  - name: fct_unused_staging_models
+    description: "This table shows each staging model with 0 children."
+    data_tests:
+      - is_empty
   - name: fct_exposure_parents_materializations
     description: "This table shows each direct parent of an exposure that is not materialized as a table or incremental."
     data_tests:

models/marts/dag/fct_unused_staging_models.sql

@@ -0,0 +1,23 @@
+-- this model finds cases where a source has no children
+
+with source_relationships as (
+    select  
+        *
+    from {{ ref('int_all_dag_relationships') }}
+    where parent_resource_type = 'model'
+    and parent_id like '%stg_%'
+    and not parent_is_excluded
+    and not child_is_excluded
+),
+
+final as (
+    select
+        parent
+    from source_relationships
+    group by 1
+    having max(distance) = 0
+)
+
+select * from final
+
+{{ filter_exceptions() }}