Implementing Slowly Changing Dimension (SCD) Type 2 for specific fields while performing Type 1 Upserts for Other fields
When working with Slowly Changing Dimensions (SCD), implementing Type 2 can be crucial to track historical data changes over time. This blog post will explain how to handle a Type 2 SCD for specific columns (e.g., field1
) while performing Type 1 updates for others. Let's break this down step by step.
Step 1: Extract and Prepare Source Data
The first step is to extract the source data and set the default metadata fields needed for the SCD Type 2 implementation.
Current_flag = 1
: Indicates the current active record.Effective_fromDT = current_date
: Marks when the current version became active.Effective_ToDT = '12/31/9999'
: A placeholder future date to signify that this record is current until replaced by a new version.
SELECT *,
1 AS Current_flag,
CURRENT_DATE AS Effective_fromDT,
'12/31/9999' AS Effective_ToDT
FROM source_table;
Step 2: End the Current Version for Records with Changes
Next, you need to end the current version of any record where the tracked field (e.g., field_1
)…