data-quality-frameworks

name	data-quality-frameworks
description	Implement data quality validation with Great Expectations, dbt tests, and data contracts. Use when building data quality pipelines, implementing validation rules, or establishing data contracts.

Data Quality Frameworks

Production patterns for implementing data quality with Great Expectations, dbt tests, and data contracts to ensure reliable data pipelines.

When to Use This Skill

• Implementing data quality checks in pipelines
• Setting up Great Expectations validation
• Building comprehensive dbt test suites
• Establishing data contracts between teams
• Monitoring data quality metrics
• Automating data validation in CI/CD

Core Concepts

1. Data Quality Dimensions

Dimension	Description	Example Check
Completeness	No missing values	expect_column_values_to_not_be_null
Uniqueness	No duplicates	expect_column_values_to_be_unique
Validity	Values in expected range	expect_column_values_to_be_in_set
Accuracy	Data matches reality	Cross-reference validation
Consistency	No contradictions	expect_column_pair_values_A_to_be_greater_than_B
Timeliness	Data is recent	expect_column_max_to_be_between

2. Testing Pyramid for Data

          /\
         /  \     Integration Tests (cross-table)
        /────\
       /      \   Unit Tests (single column)
      /────────\
     /          \ Schema Tests (structure)
    /────────────\

Quick Start

Great Expectations Setup

# Install
pip install great_expectations

# Initialize project
great_expectations init

# Create datasource
great_expectations datasource new

# great_expectations/checkpoints/daily_validation.yml
import great_expectations as gx

# Create context
context = gx.get_context()

# Create expectation suite
suite = context.add_expectation_suite("orders_suite")

# Add expectations
suite.add_expectation(
    gx.expectations.ExpectColumnValuesToNotBeNull(column="order_id")
)
suite.add_expectation(
    gx.expectations.ExpectColumnValuesToBeUnique(column="order_id")
)

# Validate
results = context.run_checkpoint(checkpoint_name="daily_orders")

Patterns

Pattern 1: Great Expectations Suite

# expectations/orders_suite.py
import great_expectations as gx
from great_expectations.core import ExpectationSuite
from great_expectations.core.expectation_configuration import ExpectationConfiguration

def build_orders_suite() -> ExpectationSuite:
    """Build comprehensive orders expectation suite"""

    suite = ExpectationSuite(expectation_suite_name="orders_suite")

    # Schema expectations
    suite.add_expectation(ExpectationConfiguration(
        expectation_type="expect_table_columns_to_match_set",
        kwargs={
            "column_set": ["order_id", "customer_id", "amount", "status", "created_at"],
            "exact_match": False  # Allow additional columns
        }
    ))

    # Primary key
    suite.add_expectation(ExpectationConfiguration(
        expectation_type="expect_column_values_to_not_be_null",
        kwargs={"column": "order_id"}
    ))
    suite.add_expectation(ExpectationConfiguration(
        expectation_type="expect_column_values_to_be_unique",
        kwargs={"column": "order_id"}
    ))

    # Foreign key
    suite.add_expectation(ExpectationConfiguration(
        expectation_type="expect_column_values_to_not_be_null",
        kwargs={"column": "customer_id"}
    ))

    # Categorical values
    suite.add_expectation(ExpectationConfiguration(
        expectation_type="expect_column_values_to_be_in_set",
        kwargs={
            "column": "status",
            : [, , , , ]
        }
    ))

    
    suite.add_expectation(ExpectationConfiguration(
        expectation_type=,
        kwargs={
            : ,
            : ,
            : ,
            :   
        }
    ))

    
    suite.add_expectation(ExpectationConfiguration(
        expectation_type=,
        kwargs={: }
    ))

    
    suite.add_expectation(ExpectationConfiguration(
        expectation_type=,
        kwargs={
            : ,
            : {: },
            : {: }
        }
    ))

    
    suite.add_expectation(ExpectationConfiguration(
        expectation_type=,
        kwargs={
            : ,  
            : 
        }
    ))

    
    suite.add_expectation(ExpectationConfiguration(
        expectation_type=,
        kwargs={
            : ,
            : ,
            : 
        }
    ))

     suite

Pattern 2: Great Expectations Checkpoint

# great_expectations/checkpoints/orders_checkpoint.yml
name: orders_checkpoint
config_version: 1.0
class_name: Checkpoint
run_name_template: "%Y%m%d-%H%M%S-orders-validation"

validations:
  - batch_request:
      datasource_name: warehouse
      data_connector_name: default_inferred_data_connector_name
      data_asset_name: orders
      data_connector_query:
        index: -1  # Latest batch
    expectation_suite_name: orders_suite

action_list:
  - name: store_validation_result
    action:
      class_name: StoreValidationResultAction

  - name: store_evaluation_parameters
    action:
      class_name: StoreEvaluationParametersAction

  - name: update_data_docs
    action:
      class_name: UpdateDataDocsAction

  # Slack notification on failure
  - name: send_slack_notification
    action:
      class_name: SlackNotificationAction
       
       
      
         
         

# Run checkpoint
import great_expectations as gx

context = gx.get_context()
result = context.run_checkpoint(checkpoint_name="orders_checkpoint")

if not result.success:
    failed_expectations = [
        r for r in result.run_results.values()
        if not r.success
    ]
    raise ValueError(f"Data quality check failed: {failed_expectations}")

Pattern 3: dbt Data Tests

# models/marts/core/_core__models.yml
version: 2

models:
  - name: fct_orders
    description: Order fact table
    tests:
      # Table-level tests
      - dbt_utils.recency:
          datepart: day
          field: created_at
          interval: 1
      - dbt_utils.at_least_one
      - dbt_utils.expression_is_true:
          expression: "total_amount >= 0"

    columns:
      - name: order_id
        description: Primary key
        tests:
          - unique
          - not_null

      - name: customer_id
        description: Foreign key to dim_customers
        tests:
          - not_null
          - relationships:
              to: ref('dim_customers')
               

        
        
           
               [, , , , ]

        
        
           
           
               

        
        
           
           
               

    
    
        
        
           
           

        
        
           
           
          
           
               

Pattern 4: Custom dbt Tests

-- tests/generic/test_row_count_in_range.sql
{% test row_count_in_range(model, min_count, max_count) %}

with row_count as (
    select count(*) as cnt from {{ model }}
)

select cnt
from row_count
where cnt < {{ min_count }} or cnt > {{ max_count }}

{% endtest %}

-- Usage in schema.yml:
-- tests:
--   - row_count_in_range:
--       min_count: 1000
--       max_count: 10000000

-- tests/generic/test_sequential_values.sql
{% test sequential_values(model, column_name, interval=1) %}

with lagged as (
    select
        {{ column_name }},
        lag({{ column_name }}) over (order by {{ column_name }}) as prev_value
    from {{ model }}
)

select *
from lagged
where {{ column_name }} - prev_value != {{ interval }}
  and prev_value is not null

{% endtest %}

-- tests/singular/assert_orders_customers_match.sql
-- Singular test: specific business rule

with orders_customers as (
    select distinct customer_id from {{ ref('fct_orders') }}
),

dim_customers as (
    select customer_id from {{ ref('dim_customers') }}
),

orphaned_orders as (
    select o.customer_id
    from orders_customers o
    left join dim_customers c using (customer_id)
    where c.customer_id is null
)

select * from orphaned_orders
-- Test passes if this returns 0 rows

Pattern 5: Data Contracts

# contracts/orders_contract.yaml
apiVersion: datacontract.com/v1.0.0
kind: DataContract
metadata:
  name: orders
  version: 1.0.0
  owner: data-platform-team
  contact: [e-mail]

info:
  title: Orders Data Contract
  description: Contract for order event data from the ecommerce platform
  purpose: Analytics, reporting, and ML features

servers:
  production:
    type: snowflake
    account: company.us-east-1
    database: ANALYTICS
    schema: CORE

terms:
  usage: Internal analytics only
  limitations: PII must not be exposed   
       


   
  
    
       
       
         
       
       
       

    
       
       
        
       
       
       

    
       
       
       
          

    
       
       
         
       

    
       
       [, , , , ]
         


   
  
    
         
         
         
         
           [, , , , ]
         


   
    
    

Pattern 6: Automated Quality Pipeline

# quality_pipeline.py
from dataclasses import dataclass
from typing import List, Dict, Any
import great_expectations as gx
from datetime import datetime

@dataclass
class QualityResult:
    table: str
    passed: bool
    total_expectations: int
    failed_expectations: int
    details: List[Dict[str, Any]]
    timestamp: datetime

class DataQualityPipeline:
    """Orchestrate data quality checks across tables"""

    def __init__(self, context: gx.DataContext):
        self.context = context
        self.results: List[QualityResult] = []

    def validate_table(self, table: str, suite: str) -> QualityResult:
        """Validate a single table against expectation suite"""

        checkpoint_config = {
            "name": f"{table}_validation",
            "config_version": 1.0,
            "class_name": "Checkpoint",
            "validations": [{
                "batch_request": {
                    : ,
                    : table,
                },
                : suite,
            }],
        }

        result = .context.run_checkpoint(**checkpoint_config)

        
        validation_result = (result.run_results.values())[]
        results = validation_result.results

        failed = [r  r  results   r.success]

         QualityResult(
            table=table,
            passed=result.success,
            total_expectations=(results),
            failed_expectations=(failed),
            details=[{
                : r.expectation_config.expectation_type,
                : r.success,
                : r.result.get(),
            }  r  results],
            timestamp=datetime.now()
        )

     () -> [, QualityResult]:
        
        results = {}

         table, suite  tables.items():
            ()
            results[table] = .validate_table(table, suite)

         results

     () -> :
        
        report = [, , ]

        total_passed = (  r  results.values()  r.passed)
        total_tables = (results)

        report.append()
        report.append()

         table, result  results.items():
            status =   result.passed  
            report.append()
            report.append()
            report.append()

              result.passed:
                report.append()
                 detail  result.details:
                      detail[]:
                        report.append()
            report.append()

         .join(report)


context = gx.get_context()
pipeline = DataQualityPipeline(context)

tables_to_validate = {
    : ,
    : ,
    : ,
}

results = pipeline.run_all(tables_to_validate)
report = pipeline.generate_report(results)


  (r.passed  r  results.values()):
    (report)
     ValueError()

Best Practices

Do's

• Test early - Validate source data before transformations
• Test incrementally - Add tests as you find issues
• Document expectations - Clear descriptions for each test
• Alert on failures - Integrate with monitoring
• Version contracts - Track schema changes

Don'ts

• Don't test everything - Focus on critical columns
• Don't ignore warnings - They often precede failures
• Don't skip freshness - Stale data is bad data
• Don't hardcode thresholds - Use dynamic baselines
• Don't test in isolation - Test relationships too

Resources

• Great Expectations Documentation
• dbt Testing Documentation
• Data Contract Specification
• Soda Core