Implement column-level PII protection for sample collection

- Add disable_samples_on_pii_columns and pii_column_tags config variables
- Create get_pii_columns_from_parent_model helper macro for column PII detection
- Modify query_test_result_rows to dynamically exclude PII columns from SELECT
- Add comprehensive integration tests for column-level PII protection
- Maintain backward compatibility with existing table-level PII detection
- Follow existing patterns for configuration, tag handling, and testing

Addresses Linear issue ELE-4850

Co-Authored-By: Yosef Arbiv <yosef.arbiv@gmail.com>

Author: devin-ai-integration[bot]

integration_tests/tests/test_column_pii_sampling.py

@@ -0,0 +1,132 @@
+import json
+
+import pytest
+from dbt_project import DbtProject
+
+SENSITIVE_COLUMN = "email"
+SAFE_COLUMN = "order_count"
+
+SAMPLES_QUERY = """
+    with latest_elementary_test_result as (
+        select id
+        from {{{{ ref("elementary_test_results") }}}}
+        where lower(table_name) = lower('{test_id}')
+        order by created_at desc
+        limit 1
+    )
+
+    select result_row
+    from {{{{ ref("test_result_rows") }}}}
+    where elementary_test_results_id in (select * from latest_elementary_test_result)
+"""
+
+TEST_SAMPLE_ROW_COUNT = 5
+
+
+@pytest.mark.skip_targets(["clickhouse"])
+def test_column_pii_sampling_enabled(test_id: str, dbt_project: DbtProject):
+    """Test that PII columns are excluded when column-level PII protection is enabled"""
+    data = [
+        {SENSITIVE_COLUMN: f"user{i}@example.com", SAFE_COLUMN: None} for i in range(10)
+    ]
+
+    test_result = dbt_project.test(
+        test_id,
+        "not_null",
+        test_args=dict(column_name=SAFE_COLUMN),
+        data=data,
+        columns=[
+            {"name": SENSITIVE_COLUMN, "config": {"tags": ["pii"]}},
+            {"name": SAFE_COLUMN},
+        ],
+        test_vars={
+            "enable_elementary_test_materialization": True,
+            "test_sample_row_count": TEST_SAMPLE_ROW_COUNT,
+            "disable_samples_on_pii_columns": True,
+            "pii_column_tags": ["pii"],
+        },
+    )
+    assert test_result["status"] == "fail"
+
+    samples = [
+        json.loads(row["result_row"])
+        for row in dbt_project.run_query(SAMPLES_QUERY.format(test_id=test_id))
+    ]
+
+    assert len(samples) == TEST_SAMPLE_ROW_COUNT
+    for sample in samples:
+        assert SENSITIVE_COLUMN not in sample
+        assert SAFE_COLUMN in sample
+
+
+@pytest.mark.skip_targets(["clickhouse"])
+def test_column_pii_sampling_disabled(test_id: str, dbt_project: DbtProject):
+    """Test that all columns are included when column-level PII protection is disabled"""
+    data = [
+        {SENSITIVE_COLUMN: f"user{i}@example.com", SAFE_COLUMN: None} for i in range(10)
+    ]
+
+    test_result = dbt_project.test(
+        test_id,
+        "not_null",
+        test_args=dict(column_name=SAFE_COLUMN),
+        data=data,
+        columns=[
+            {"name": SENSITIVE_COLUMN, "config": {"tags": ["pii"]}},
+            {"name": SAFE_COLUMN},
+        ],
+        test_vars={
+            "enable_elementary_test_materialization": True,
+            "test_sample_row_count": TEST_SAMPLE_ROW_COUNT,
+            "disable_samples_on_pii_columns": False,
+        },
+    )
+    assert test_result["status"] == "fail"
+
+    samples = [
+        json.loads(row["result_row"])
+        for row in dbt_project.run_query(SAMPLES_QUERY.format(test_id=test_id))
+    ]
+
+    assert len(samples) == TEST_SAMPLE_ROW_COUNT
+    for sample in samples:
+        assert SENSITIVE_COLUMN in sample
+        assert SAFE_COLUMN in sample
+
+
+@pytest.mark.skip_targets(["clickhouse"])
+def test_column_pii_sampling_all_columns_pii(test_id: str, dbt_project: DbtProject):
+    """Test behavior when all columns are tagged as PII"""
+    data = [
+        {SENSITIVE_COLUMN: f"user{i}@example.com", SAFE_COLUMN: i} for i in range(10)
+    ]
+
+    test_result = dbt_project.test(
+        test_id,
+        "not_null",
+        test_args=dict(column_name=SAFE_COLUMN),
+        data=data,
+        columns=[
+            {"name": SENSITIVE_COLUMN, "config": {"tags": ["pii"]}},
+            {"name": SAFE_COLUMN, "config": {"tags": ["pii"]}},
+        ],
+        test_vars={
+            "enable_elementary_test_materialization": True,
+            "test_sample_row_count": TEST_SAMPLE_ROW_COUNT,
+            "disable_samples_on_pii_columns": True,
+            "pii_column_tags": ["pii"],
+        },
+    )
+    assert test_result["status"] == "pass"
+
+    samples = [
+        json.loads(row["result_row"])
+        for row in dbt_project.run_query(SAMPLES_QUERY.format(test_id=test_id))
+    ]
+
+    assert len(samples) == TEST_SAMPLE_ROW_COUNT
+    for sample in samples:
+        assert "_no_non_pii_columns" in sample
+        assert sample["_no_non_pii_columns"] == 1
+        assert SENSITIVE_COLUMN not in sample
+        assert SAFE_COLUMN not in sample

macros/edr/materializations/test/test.sql

@@ -51,7 +51,8 @@
 {% macro handle_dbt_test(flattened_test, materialization_macro) %}
   {% set result = materialization_macro() %}
   {% set result_rows = elementary.query_test_result_rows(sample_limit=elementary.get_config_var('test_sample_row_count'),
-                                                         ignore_passed_tests=true) %}
+                                                         ignore_passed_tests=true,
+                                                         flattened_test=flattened_test) %}
   {% set elementary_test_results_row = elementary.get_dbt_test_result_row(flattened_test, result_rows) %}
   {% do elementary.cache_elementary_test_results_rows([elementary_test_results_row]) %}
   {% do return(result) %}
@@ -103,19 +104,43 @@
   {% do return(new_sql) %}
 {% endmacro %}
 
-{% macro query_test_result_rows(sample_limit=none, ignore_passed_tests=false) %}
+{% macro query_test_result_rows(sample_limit=none, ignore_passed_tests=false, flattened_test=none) %}
   {% if sample_limit == 0 %} {# performance: no need to run a sql query that we know returns an empty list #}
     {% do return([]) %}
   {% endif %}
   {% if ignore_passed_tests and elementary.did_test_pass() %}
     {% do elementary.debug_log("Skipping sample query because the test passed.") %}
     {% do return([]) %}
   {% endif %}
+  
+  {% set pii_columns = [] %}
+  {% if flattened_test %}
+    {% set pii_columns = elementary.get_pii_columns_from_parent_model(flattened_test) %}
+  {% endif %}
+  
+  {% set select_clause = "*" %}
+  {% if pii_columns %}
+    {% set query_to_get_columns %}
+      with test_results as (
+        {{ sql }}
+      )
+      select * from test_results limit 0
+    {% endset %}
+    {% set columns_result = elementary.run_query(query_to_get_columns) %}
+    {% set all_columns = columns_result.column_names %}
+    {% set safe_columns = all_columns | reject("in", pii_columns) | list %}
+    {% if safe_columns %}
+      {% set select_clause = safe_columns | join(", ") %}
+    {% else %}
+      {% set select_clause = "1 as _no_non_pii_columns" %}
+    {% endif %}
+  {% endif %}
+  
   {% set query %}
     with test_results as (
       {{ sql }}
     )
-    select * from test_results {% if sample_limit is not none %} limit {{ sample_limit }} {% endif %}
+    select {{ select_clause }} from test_results {% if sample_limit is not none %} limit {{ sample_limit }} {% endif %}
   {% endset %}
   {% do return(elementary.agate_to_dicts(elementary.run_query(query))) %}
 {% endmacro %}

macros/edr/system/system_utils/get_config_var.sql

@@ -55,6 +55,8 @@
     'disable_skipped_test_alerts': true,
     'dbt_artifacts_chunk_size': 5000,
     'test_sample_row_count': 5,
+    'disable_samples_on_pii_columns': false,
+    'pii_column_tags': ['pii', 'personal', 'sensitive'],
     'edr_cli_run': false,
     'max_int': 2147483647,
     'custom_run_started_at': none,

macros/edr/system/system_utils/is_pii_column.sql

@@ -0,0 +1,42 @@
+{% macro get_pii_columns_from_parent_model(flattened_test) %}
+  {% set pii_columns = [] %}
+  
+  {% if not elementary.get_config_var('disable_samples_on_pii_columns') %}
+    {% do return(pii_columns) %}
+  {% endif %}
+  
+  {% set parent_model_unique_id = elementary.insensitive_get_dict_value(flattened_test, 'parent_model_unique_id') %}
+  {% set parent_model = elementary.get_node(parent_model_unique_id) %}
+  
+  {% if not parent_model %}
+    {% do return(pii_columns) %}
+  {% endif %}
+  
+  {% set column_nodes = parent_model.get("columns") %}
+  {% if not column_nodes %}
+    {% do return(pii_columns) %}
+  {% endif %}
+  
+  {% set pii_column_tags = elementary.get_config_var('pii_column_tags') %}
+  {% if pii_column_tags is string %}
+    {% set pii_column_tags = [pii_column_tags] %}
+  {% endif %}
+  
+  {% for column_node in column_nodes.values() %}
+    {% set config_dict = column_node.get('config', {}) %}
+    {% set config_tags = config_dict.get('tags', []) %}
+    {% set global_tags = column_node.get('tags', []) %}
+    {% set meta_dict = column_node.get('meta', {}) %}
+    {% set meta_tags = meta_dict.get('tags', []) %}
+    {% set all_column_tags = config_tags + global_tags + meta_tags %}
+    
+    {% for pii_tag in pii_column_tags %}
+      {% if pii_tag in all_column_tags %}
+        {% do pii_columns.append(column_node.get('name')) %}
+        {% break %}
+      {% endif %}
+    {% endfor %}
+  {% endfor %}
+  
+  {% do return(pii_columns) %}
+{% endmacro %}