ETL Pipelines
Medium Priority15 min readUpdated October 8, 2026
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The data a business needs is rarely in one place. Orders live in one database, payments in a third-party service, support tickets in a helpdesk tool, and website clicks in an analytics service. Each system has its own format, its own IDs, and its own quirks. Getting all of that into one place where people can query and trust it is the job of an ETL pipeline.
In this chapter, we will look at what ETL pipelines are, how each of the three stages works, how pipelines are scheduled and kept reliable, and how the newer ELT approach changes where transformations happen.