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ELT stands for Extract, Load, and Transform. It's a process by which data is replicated from a source to a destination (often a data warehouse).

What is ELT (Extract, Load, Transform)?

ELT is a form of data integration, and an important step in the cycle of company data. It’s how data points are sourced, consolidated, and rendered uniform so they can then be used for various data activation purposes.

ELT stands for Extract, Load, Transform. It’s the practice through which you bring raw data from various sources together in your warehouse and clean it up to make it usable.

  1. Extract: In this first step of the process, your data is copied from its source, whether that’s a SaaS tool, production database, or some other system that generates data. The data may be ingested as a complete set, or select data points might be ingested based on preset specifications.
  2. Load: Next up, your data is loaded directly into the target destination. Think of the extraction as the ‘copy’ stage, the load as the ‘paste’ stage, where an identical duplicate of your data is created. Usually, this will be your data warehouse like Snowflake, BigQuery, or one of the other major data warehouses out there.
  3. Transform: Finally, your data is transformed. Your warehouse will sort, clean, and unify your data from various sources so it all fits into the same norms. While your data is made uniform, part or all of its original configuration will remain available should you need it for in-depth analysis, reporting, or other uses.


In the past, data integration was primarily done through the ETL (Extract, Transform, Load) method. The main difference between ELT and ETL is the order of things. ETL involves an additional stage where data is transformed in a staging area before being loaded into the warehouse.

As cloud-based data warehousing solutions have risen in popularity, ELT is becoming a more common data integration technique. Maintaining the raw data in your warehouse allows for more flexibility and deeper analysis. It’s also far less time consuming and much more scalable, especially today when most companies have such vast quantities of data and tens if not hundreds of data sources.

Read our full blog post to learn more about ELT and how it's different from ETL

Performing ELT with Weld

ELT is a core functionality of Weld, the data operations platform built for data analysts. With dozens of pre-built ELT pipelines, you can easily start streaming data into your warehouse in a matter of minutes with Weld. Data modelling and reverse-ETL are other core features of Weld, bringing all of your core data operations into one space.

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Tired of scattered data? Sync data to your data warehouse with Weld in minutes with our powerful ETL, SQL Transformations, Reverse ETL and AI Assistant, Ed - connected to 100+ apps, files and databases.

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