Do you prefer heavy data transformations during early ETL or later in modelling? Why?

Ishan
Updated on June 16, 2025 in

I’m exploring best practices in designing data pipelines and want to understand how different teams handle computationally intensive transformations. Some advocate for doing it early during ETL to keep models clean and fast, while others prefer flexibility and defer transformations to the modelling stage. Curious to hear what’s worked for others and why.

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on June 16, 2025

As someone who’s spent considerable time with Power BI, I can definitely relate to discovering those “hidden gems” that completely change how you work with data! Calculation Groups are indeed one of those underutilized powerhouses.

Here are a few other lesser-known features that I’ve found incredibly valuable but seem to fly under the radar:

Field Parameters – This is a game-changer for creating dynamic visuals where users can switch between different measures or dimensions on the fly. Instead of creating multiple similar reports, you can build one flexible visual that adapts based on user selection. It’s perfect for executive dashboards where stakeholders want to toggle between revenue, profit, units sold, etc.

Composite Models with DirectQuery – Many people stick to either Import or DirectQuery, but the hybrid approach lets you combine both in the same model. You can keep your large fact tables in DirectQuery for real-time data while importing smaller dimension tables for better performance. It’s particularly useful for scenarios where you need both historical analysis and up-to-the-minute operational data.

What-If Parameters – These are fantastic for scenario modeling and sensitivity analysis. You can create sliders that let users adjust assumptions (like growth rates or discount percentages) and see how they impact your calculations in real-time. I’ve used this for budget planning and forecasting presentations where executives want to explore different scenarios interactively.

Q&A Visual Natural Language Queries – While many know about the Q&A feature at the service level, fewer people utilize the Q&A visual within reports. It allows end-users to ask questions in plain English directly within your dashboard, making your reports more accessible to non-technical users.

Smart Narrative Visual – This automatically generates written insights about your data, highlighting key trends, outliers, and comparisons. It’s like having an AI analyst write commentary for your dashboards, which is incredibly useful for executive summaries.

The pattern I’ve noticed is that many of these powerful features require a bit more setup initially, but they pay massive dividends in terms of user experience and maintenance efficiency. What’s your experience been with Calculation Groups? Have you found them as transformative as they promise to be for time intelligence scenarios?

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on June 3, 2025

My name is Jogn

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on May 31, 2025

my name is john

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on May 7, 2025

Ah, the age-old debate! It really boils down to a trade-off between upfront cost and downstream flexibility. Here’s a glimpse into what I’ve observed works for different teams:

Early Transformation (ETL Focus):

Pros:

-Clean and Fast Models: Models receive pre-processed, analysis-ready data, leading to faster training and potentially simpler model architectures.

-Reduced Redundancy: Transformations are defined and executed once, avoiding repetition across multiple models.

-Improved Data Governance: A centralized ETL process can enforce data quality standards and consistency.

-Resource Optimization: Heavy lifting is done in dedicated infrastructure optimized for ETL.

Cons:

-Reduced Flexibility: Changes to transformations require modifying the ETL pipeline, which can be time-consuming and impact all downstream processes.

-Potential for Information Loss: Aggregations or filtering done too early might discard information that could be useful for specific modeling tasks later.

-“One-Size-Fits-All” Challenge: Transformations might not be optimal for every modeling objective.

 

Deferred Transformation (ELT/Modeling Focus):

Pros:

-Maximum Flexibility: Data scientists have more control over feature engineering and can tailor transformations to specific model requirements.

-Faster Iteration: Experimenting with different transformations is quicker as it’s contained within the modeling workflow.

-Preservation of Granularity: Raw data is kept longer, allowing for more diverse analyses and future use cases.

Cons:

-Computational Burden on Modeling Infrastructure: Training can become slower and more resource-intensive with complex, on-the-fly transformations.

-Potential for Inconsistency: Different teams or individuals might implement the same transformations in slightly different ways.

-Increased Complexity: Managing transformations within multiple modeling pipelines can become challenging.

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