Eliminate Costly Data Quality Problems – By Building the Right Foundation

According to Gartner research, “the average financial impact of poor data quality on organizations is $9.7 million per year.” In this article, I will discuss how to build the foundation for a governed data quality Data Lake that can drive your self-service analytics, improve your time to market, improve efficiency, and reduce overall costs.

The challenge in getting value out of data can be compared to mining for gold.

Gold miners in Alaska continuously run massive amounts of raw dirt through a processing plant in order to extract a comparatively small amount of gold flecks and, with luck,  some nice-sized nuggets. Similarly,  knowledge workers have to spend the majority of their time processing vast amounts of raw data to actually extract valuable insights. 

Combining, cleaning, sorting, merging, scrubbing, and fixing data for use is a laborious task involving quite a bit of data engineering rigor.

A little data science humor: A data scientist spends 95% of their time dealing with problems with the data and the other 5% complaining about how much time they spend dealing with data problems!

Just as a dump truck full of unprocessed “paydirt” holds only the potential of valuable gold, data at rest also only has potential value. The goal is to monetize this potential value by creating a kind of processing plant or refinery for the data. Ideally, companies should make the process as efficient, automated, and repeatable as possible. Such a refinery will ingest all types of raw data and, more importantly, process it through stages of increasing data quality. The idea is to continuously produce fresh, quality data ready for consumption. 

Several basic patterns exist for setting up a data lake to enable efficient data flow and thereby enable the refinery. A data lake should address data quality, implement governance, and enable self-service exploratory analysis for trusted datasets. These trusted datasets allow analysts and data scientists to expertly refine and monetize the data and produce valuable insights. Trusted datasets also provide a single version of the truth.

Consider the reference diagram below:

A key component of our data lake is how we set up the zones or buckets. The popular approach is to implement a multi-hop data architecture which allows us to deal with stages of data quality at each hop or zone. 

Extract Transform Load (ETL) vs Extract Load Transform (ELT) 

One key difference exists when making the paradigm shift from traditional ETL to ELT. Traditional ETL bakes the transformation step into the middle of the extraction and loading process. This leads to ongoing maintenance costs and fragility since any changes require rewriting complex transformation logic code. ELT delays the transformation step until all data is loaded from the source system to the data lake destination. Benefits include:  enables continuous data loading, allows as needed application of transformations for analysis , eliminates break/fix maintenance, and facilitates building failure proof data pipelines. 

The Lake Data Quality Zones


Sometimes this additional landing pre-raw-zone is needed to work out extra complex ELT logic depending on the source system integration.


Land the data here; this is raw and volatile to failure. No modification is made to the data here and it can be reprocessed. If you consider brittle ETL processes, many data quality issues related to infrastructure, schema changes, breaking jobs, etc. are isolated to this zone and remediated here. It is highly desirable to stick to an ELT pattern in data pipelines.


The data are typically translated from the raw formats and extracted files to an optimized columnar format, like parquet. Typically, some light scrubbing and de-duplication is done at this stage. These data are in a data quality state of “usable” and ready for downstream consumption. These data provide a single version of the truth from which all downstream data wrangling flows.  Automation of both data quality rules and privacy controls can be implemented in this zone. Examples include standardizing to common date formats and PII detection/remediation for compliance. 


The terminal data quality zone in the data lake is the analytics zone. Aggregated and curated datasets live here. This is an ideal location to save and share curated datasets. Data stewardship, managing folder locations, permissions, and sharing for datasets can be implemented in this zone. 

Addressing Automation and Data Quality Processing

The AWS Glue family of services includes tools to discover, integrate, prepare, clean and transform data at any scale. ELT processing can be built with serverless glue data transformation activities as part of automated continuous data pipelines. Keeping our data moving and as fresh as possible through the quality zones in the data lake is critical. Additional operational features can be added such as feedback loops, SLA monitoring, and alerts on pipelines feeding the lake.

Additional activities for data quality handling in the lake can include:

  • Data lake data quality layers IAM roles & permissions
  • Creating data quality rules
  • Handling schema evolution
  • Implementing rejected records handling 
  • Managing lifecycle policies
  • Using machine learning to address record matching
  • AI services like AWS Macie for sensitive automated data detection and protection

Once ELT pipelines are in place that continuously process data from raw to stage zones, the next steps are governance, stewardship, metadata management, and enabling the self-service capability for data wrangling.

Using AWS Lake Formation, the data steward will set up the following:

Data Stewardship for Self-Service Enablement

Data Stewards manage permissions, control metadata tagging and grouping of tags into categories, often referred to as taxonomies and ontologies in metadata management.

  • Configure workspace
  • Configure user access
  • Configure tagging and classification ontologies (PII, PHI, HIPAA, GDPR, Data Masking)
  • Setup publishing
  • Assign sharing permissions

The key to enabling self-service is the existence of a centralized metadata catalog combined with a vital data governance stewardship function. With AWS Lake Formation, companies can set up centralized data governance on top of their data lakes. Self-service tools like AWS Athena and AWS Glue DataBrew and AWS Sagemaker Data Wrangler are used to clean and prepare data sets for analytics and machine learning. These tools connect directly to lake formation’s centralized data catalog for querying and analysis. Cleansed datasets are saved to the analytics zone; metadata are saved to the catalog. 

The above approach connects knowledge workers to a continuous feed of trusted data. This means faster answers to business critical questions. In gold mining, the more paydirt moved through an efficient refining process, the more gold recovered. Let us help you kick-start your  “data refinery!”  

Caylent’s data engineering experts will work with you to build a foundational data lake and enable your teams to use no-code solutions for wrangling and exploring your data. Our Serverless Data Lake Catalyst will shorten your time to market from months to weeks and set you up to easily grow your data lake by scaling ingest sources through low-code solutions.

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