Exam PL-300 topic 2 question 88 discussion

https://learn.microsoft.com/en-us/power-bi/guidance/power-query-referenced-queries "In the example, if Query1 is redesigned as a dataflow entity, Query2, Query3, and Query4 can use it as a data source. With this design, the entity sourced by Query1 will be evaluated only once."

Query1 is referenced by multiple other queries, which means its logic is executed multiple times during refresh — a major performance bottleneck. By turning Query1 into a dataflow, you centralize and pre-process the customer data once, outside the semantic model. The other queries (Query2, Query3, Query4) can then connect to the dataflow, avoiding redundant processing and significantly improving refresh performance.

Dataflows allow data to be processed and reused across multiple datasets, reducing refresh time and centralizing logic.

"We recommend you create a dataflow instead. Using a dataflow can improve data refresh time and reduce impact on your data sources."

The best option is A. Run the Table.Buffer function in Query1. When Query1 is referenced by the other queries, Power Query might re-evaluate it multiple times during a refresh. By applying the Table.Buffer function in Query1, you force its results to be cached in memory. This ensures that the customer data is loaded only once, and the buffered result is reused by the subsequent queries, thereby improving the data refresh performance without incurring extra costs.

Problem Recap: A Power BI semantic model with four queries (Query1, Query2, Query3, Query4). Query1 loads customer data and is referenced by the other queries. Data refresh is slow, and you need to improve refresh time while minimizing costs. Key Constraints: avoid additional costs (e.g., Premium or Pro licenses). improve refresh performance without increasing resource usage. Solution: A. Run the Table.Buffer function in Query1. The Table.Buffer function loads the data from Query1 into memory, which can speed up subsequent transformations and queries that reference Query1. This is particularly useful when Query1 is referenced multiple times (e.g., by Query2, Query3, and Query4), as it reduces the need to reload the data from the source. https://learn.microsoft.com/de-de/powerquery-m/table-buffer

Gemini say so, seems reasonable. When you use Table.Buffer on a query (like Query1 in this case), you force Power BI to fully load the results of that query into memory. Because Query1 is referenced by the other three queries, this buffering has a significant positive impact. Instead of Query2, Query3, and Query4 each re-evaluating Query1 every time they are refreshed, they can simply reuse the buffered copy already in memory. This drastically reduces redundant calculations and speeds up the overall refresh process.

C is the correct answer . Please open this link:https://learn.microsoft.com/en-us/power-bi/guidance/power-query-referenced-queries.

Question is You need to improve the data refresh time so it should be A The Table.buffer function loads the entire table into memory when it's first accessed, which helps improve performance by reducing the need to fetch data repeatedly from the source. If Query1 is used in other queries, applying Table.buffer ensures all the customer data is loaded into memory once, speeding up the refresh process. Reconfiguring Query1 as a dataflow could help with reusability and organizing transformations, but it doesn’t directly improve refresh times for the existing model.

When a query in Power BI is referenced multiple times (as Query1 is referenced by Query2, Query3, and Query4 in this scenario), Power BI can execute Query1 multiple times during the data refresh process. This redundant execution slows down the refresh time. The Table.Buffer function helps optimize this by loading the data from Query1 into memory so that subsequent queries can reuse the buffered data, preventing repetitive execution. why not C : While using a dataflow can offload processing to the Power BI Service, this introduces additional costs (Premium or Pro licenses). The question specifies that the solution must minimize costs.

A is the correct answer because for C you will need to use a premium workspace or PPU

create a dataflow instead. Using a dataflow can improve data refresh time and reduce impact on your data sources.

I vote for option C. We should copy the code in Query 1 t ouse it to create dataflow with it... Table.buffer could improve performace by preventing multiple scans of the SOURCE table during transformations; since queries 2, 3 and 4 are referenced to Query 1, they are not scanning the source table but the referenced query which is retrieving the data from the source

Its C: your comment is too short

https://learn.microsoft.com/en-us/power-bi/guidance/power-query-referenced-queries

Table.Buffer will keep the data in memory as buffer. So there wont be any changes in data. this is similar to referencing the data.

Run the Table.Buffer function in Query1