Delta Live Tables use case

Floody
New Contributor II

‎03-18-2024 06:31 AM

Hi all,

We have the following use case and wondering if DLT is the correct approach.

Landing area with daily dumps of parquet files into our Data Lake container.

The daily dump does a full overwrite of the parquet each time, keeping the same file name.

The idea would be to re-process the whole parquet each time and manage the delta in the bronze table with SCD 2.

Suggestions on the best approach would be helpful.

Cheers

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Sidhant07
Databricks Employee
Databricks Employee

‎12-08-2024 11:33 PM

Using DLT for Your Use Case

DLT can be a good fit for your scenario, especially when implementing Slowly Changing Dimension (SCD) Type 2. Here's how you can approach this:

  1. Ingestion with Auto Loader: Use Auto Loader to ingest the daily parquet files into your bronze layer. This handles the full overwrites efficiently.
  2. Bronze Layer Processing: Create a bronze table using DLT that reads from the landing area.
  3. SCD Type 2 Implementation: Implement SCD Type 2 in the silver layer using DLT's APPLY CHANGES syntax.

Implementation Approach

Here's a high-level implementation strategy:

Bronze Layer:

@Dlt.table
def bronze_table():
return (
spark.readStream.format("cloudFiles")
.option("cloudFiles.format", "parquet")
.load("/path/to/landing/area")
)

Silver Layer with SCD Type 2:

dlt.create_streaming_table("silver_table_scd2")

dlt.apply_changes(
target = "silver_table_scd2",
source = "bronze_table",
keys = ["your_primary_key"],
sequence_by = col("file_modification_time"),
stored_as_scd_type = "2"
)

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