Facing size related issues while creating a custom semantic model in Microsoft Fabric

[anonymouss]

I am getting this below error:
Data source error: Database '1bf8d3cc-db45-4910-8129-4886335955e5' exceeds the maximum size limit on disk; the size of the database to be loaded or committed is 26843791360 bytes, and the valid size limit is 26843545600 bytes. If using Power BI Premium, the maximum DB size is defined by the customer SKU size (hard limit) and the max dataset size from the Capacity Settings page in the Power BI Portal. Cluster URI: DF-MSIT-SCUS-redirect.analysis.windows.net Activity ID: 4f4c3017-716d-48f6-9643-e6ed1b1d907f Request ID: 64c9e882-9d50-0fcc-5d41-ad3ea1318770 Time: 2024-08-09 11:02:25Z

I have created a semantic model from Lakehouse in Fabric. The lakehouse has shortcuts pointing to ADLS Gen2 delta tables. Now, when I create this semantic model the size of the model is Exceeding my Fabric License limit(25GB). This should not happen because the semantic model is created on shortcuts, which are just pointers to the data. I am not sure why the Semantic model size is touching 25GB here. I am not importing any tables to the semantic model (not that I know of), but still the size of the model is exceeding 25GB. What can be the possible reasons here? Is there a way to reduce the size of the semantic model, without disturbing the tables and their schema? Is there any configuration that I am missing here?

Additionally, I have observed that the default semantic model of the lakehouse is of 1MB in size. But when I create a Custom semantic model on that lakehouse selecting tables from that lakehouse the size of the custom semantic model is hugely increasing,

[v-shex-msft · Accepted solution]

Hi @anonymouss,

I'd like to suggest you take a look at the following document semantic model memory usage parts to know more about the model resource usages in different operations and steps:

What is Power BI Premium? - Power BI | Microsoft Learn

Semantic model operations such as queries are subject to individual memory limits. To illustrate the restriction, consider a semantic model with an in-memory footprint of 1 GB, and a user initiating an on-demand refresh while interacting with a report based on the same semantic model. Three separate actions determine the amount of memory attributed to the original semantic model, which may be larger than two times the semantic model size. The total amount of memory used by one Power BI item can't exceed the SKU's Max memory per semantic model allocation.

The model will apply 'Loading the semantic model' and 'Refreshing the semantic model' operations. So I suppose they will temporary occupancy the at least equal to the fact data size of memory resources when load data from shortcut to initialize.

Regards,

Xiaoxin Sheng