What is type 1 vs type 2 SCD at a high level?

< 1 min read

Type 1 and Type 2 are ways to handle changes in dimension data.
In Type 1, we overwrite the old value with the new value.
There is no history maintained.
For example, if a customer changes city from Chennai to Bangalore, we just update the city column.
This is useful when historical tracking is not important, like correcting spelling mistakes.
In Type 2, we keep history by creating a new record.
We usually add columns like effective_date, end_date, and is_active flag.
For example, if a customer upgrades from Basic to Premium, we insert a new row and expire the old one.
This helps in reporting historical data accurately, like revenue by membership type at a specific time.

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