Watermarking vs CDC: Strategies for Efficient Data Loading

View profile for Prasad Chokkakula

Data Engineer with 5+yrs of experience in Azure | Databricks | PySpark | Hadoop | Scalable ETL Pipelines

In data engineering, one of the most important questions we face is: 👉 How do we load only the new or changed data efficiently? Two widely used strategies are: Watermarking and Change Data Capture (CDC). Both avoid costly full reloads, but their use-cases differ. Here’s a breakdown ⬇️ 📍 Watermarking (Incremental Loads) ✅ Tracks the last processed point (often a timestamp, identity column, or version number). ✅ Easy to configure in ADF copy activity or Databricks notebooks. ✅ Best for append-only data: IoT events, transaction logs, telemetry, clickstreams. ⚠️ Limitation: If source data is updated or deleted, watermarking won’t capture it. 📍 Change Data Capture (CDC) ✅ Captures inserts, updates, and deletes directly from the source (via SQL Server CDC, Debezium, ADF Change Tracking, etc.). ✅ Ensures true data fidelity in Delta Lake – including Slowly Changing Dimensions (SCDs) and full auditing. ✅ Works best for OLTP systems, ERP/CRM migrations, and scenarios where business rules depend on changes. ⚠️ Slightly more complex setup and often requires extra infra (logs, Kafka, CDC tables). 🚀 In Real Projects Start with Watermarking → when the source is append-only and simplicity is key (ex: sales transactions, telemetry feeds). Move to CDC → when you need complete historical accuracy (SCD Type 2, audit logs, backtracking business events). Use Both Together → Watermarking as a baseline for detecting new records. CDC for handling updates/deletes on top of the incremental load. Example: A retail system where new sales come via Watermarking but price updates/cancellations are handled via CDC. 🔹 Key takeaway: It’s not always Watermarking vs CDC. In modern data platforms, you often need both strategiesworking together for a truly resilient data pipeline. #DataEngineering #AzureDataFactory #Databricks #DeltaLake #CDC #Watermarking #ETL #BigData #Azure #DataPipelines #Toronto #Database #sql #data #engineering #python #spark

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Prakash Nanda Panda

Senior Data Engineer at Fractal | Python | SQL | PySpark | Azure Data Factory | Azure Databricks | ADLS

3w

Great insights, Prasad! Your breakdown of Watermarking and Change Data Capture highlights the nuances in data engineering perfectly. It's clear that choosing the right strategy can significantly enhance data pipeline efficiency. Thank you for sharing your expertise!

Abhishek Agrawal

Data Engineer at ALDI DX ⭐ | Azure Data Factory | Azure Databricks | Big Data | Spark | Data Warehouse | Fabric | ☁️ Certified

3w

Thanks for sharing

Ashish Kumar

🧠 Building Scalable LLM/RAG Platforms | LLMOps/MLOps | On-Prem & ☁️ Cloud (GCP/AWS/Azure) | Tech Lead @ Thales | 🔧 DevOps • 🗄️ Data Eng | Python • Databricks • ETL | K8s • Terraform | MLflow • Vertex AI • SageMaker

2w

Insightful

Mohamed MMADI

Freelance Data Analyst| Business Analyst | Expert Power BI - Azure | Business Intelligence | Investisseur

3w

Really like how you framed this 🚀 In my experience, teams often default to full reloads simply because they underestimate how fragile pipelines become when governance isn’t set from the start. I’ve seen cases where 60–70% of downstream dashboards broke — not because of tooling, but because changes weren’t captured correctly upstream. Curious — when you’ve introduced CDC in projects, what’s been the biggest blocker: infra complexity, cost, or team skills?

Rui Carvalho

Data Engineer @IWG | Databricks | Spark | SQL Server | MS Fabric | Speaker at Data Events | Medium Writer ✍️

3w

Good explanation. Its all about how the data behaves, some time you need to updste old records , sometimes just get the new

Dhiraj Gupta

Senior Data Engineer - AWS @ Quantiphi | Tech YouTuber | 1xAWS | 1xSnowflake | SQL | PySpark | Spark | Python |Databricks |Pandas | Java | DSA | Kafka | Data Modeling | QuerySurge | Machine Learning| Power BI

2w

Agreed. We need to choose them wisely

RAMBABU DONGARA

Sr Tech Lead | Pyspark | BI Delivery Expert (Data visualization, Power BI, SQL, Kusto, ADF, SSAS, Data Modeling, Data Analysis, Tableau) | Ex -PepsiCo, TCS, CYIENT

3w

Great insight

Subash Chandra Bose R

AWS Data Engineer @ CTS | Ex TCS | ETL & Data Pipeline Specialist | AWS Redshift | SQL, Python (Pandas)

2w

The loading pattern speaks here from Delta to CDC, thanks for sharing

Carolina Russ

Growth Manager @ Weld | Making data accessible everywhere.

2w

Great breakdown! Thanks for sharing!

M. Abdullah Bin Aftab

Data Engineer | 3x AWS | 1x Azure | DWH | ETL/ELT | Databricks | PySpark | Python | SQL | Airflow | Airbyte | dbt | Snowflake | AWS Cloud Club Regional Captain | Beta MLSA | Postman Student Leader

2w

I want to share my personal experience: when we made our infra we haven't taken care about to capture changes and track them, things were going smooth at least for 6 month, then we have to migration now the story getting interesting turn apparently all the stakeholders apparently asking for points and asking about the history the little changes in the data that we haven't done in our infra to capture, then we realized we have to process thing so we are using now "water marking" and "CDC" Thanks to Prasad Chokkakula this knowledge is very important not only the Pipelines are enough.

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