topic Re: Dataflow is creating complex type column in Lakehouse tables from Decimal or Currency type Yet A in Data Engineering

Dataflow is creating complex type column in Lakehouse tables from Decimal or Currency type Yet Again

lemaribdb — Fri, 04 Jul 2025 12:52:23 GMT

Hi, I see similar topci got resolved as it stopped hapening. But I encountered it just now, my currency type cols are becoming complex type in Lakehouse...
It's using replace, properly mapped cols and types etc

Re: Dataflow is creating complex type column in Lakehouse tables from Decimal or Currency type Yet A

BhaveshPatel — Sat, 05 Jul 2025 09:32:33 GMT

Not clear. Where is the dataflows currancy type col. You should give some screenshots....???

Re: Dataflow is creating complex type column in Lakehouse tables from Decimal or Currency type Yet A

john_li88 — Sat, 05 Jul 2025 15:09:06 GMT

I'm experiencing same issue.

Re: Dataflow is creating complex type column in Lakehouse tables from Decimal or Currency type Yet A

v-echaithra — Mon, 07 Jul 2025 04:43:47 GMT

Hi @lemaribdb ,

Thank you for reaching out to Microsoft Community.

Bsed on your description I understand that the columns that are Currency type in DFG2 are Complex in lakehouse.
This is a known issue and a temporary bug in Fabric Dataflow Gen2 that affected decimal and currency columns when they were written to Lakehouse tables.
Reference: Fabric known issues - Microsoft Fabric | Microsoft Learn.

If you have a Pro license, please consider raising support ticket at https://admin.powerplatform.microsoft.com/newsupportticket/powerbi
otherwise you can raise an issue at https://community.fabric.microsoft.com/t5/Issues/idb-p/Issues .

Best Regards,
Chaithra E.

Re: Dataflow is creating complex type column in Lakehouse tables from Decimal or Currency type Yet A

lemaribdb — Mon, 07 Jul 2025 08:34:30 GMT

Hi, I thought you would just trust me haha.
Lakehouse view:

The actual DFG2 feed:

Re: Dataflow is creating complex type column in Lakehouse tables from Decimal or Currency type Yet A

BhaveshPatel — Mon, 07 Jul 2025 08:42:04 GMT

Hi @lemaribdb

Databricks Delta Lake is an open source data lakehouse and implemented first even before Microsoft.

There is no data type called Currency Data Type in Delta Lake. It is decimal data type that are converted to Currency Data Type in Fabric SQL. For goodness of Microsoft

You can see the below screenshots of Delta Lake aka Lakehouse.

Re: Dataflow is creating complex type column in Lakehouse tables from Decimal or Currency type Yet A

lemaribdb — Mon, 07 Jul 2025 08:47:10 GMT

Yes I'm aware but what is the solution then? The only option PQ for this type of data is either Whole Number, Decimal Number or currency. Where whole numbers is not precise enough and decimal number is unnecesary precision.
Shouldn't currency type just transform it into a decimal with 2 precision in Lakehouse, not a complex type? Is it beacuse currency tries to keep some currency type metadata?
Is my best bet just rounding those to 2 decimal place and feeding as decimal?

Re: Dataflow is creating complex type column in Lakehouse tables from Decimal or Currency type Yet A

BhaveshPatel — Mon, 07 Jul 2025 08:50:10 GMT

Yes that is correct. Convert the data to decimal type with precision of 2 in Delta Lake aka Lakehouse