Power Query M: 1 query, twice referenced => data loading three times?!

[chefe]

Hello,

I'm importing a folder of text files. The combined contents are stored in "F" file.

I then reference F two times and apply a different filter to each  with F1 and F2.

Now, when refreshing it seems that all three querying the source files, generating long loading times. Also the files are a couple of hundred MBs in size.

My guess would have been that only F reloads the data. F1 and F2 then near-instantaneously being up-to-date as well. But this does not seem to be the case.

Is this expected behaviour?

Kind regards

[v-xjiin-msft]

Hi @chefe,

To improve the performance of referencing table, you need to buffer your table. Like: Table.Buffer(YourTable). After adding the Table.Buffer, when your refresh your reference, it will not access the database again.

For more details, please refer: 

https://community.powerbi.com/t5/Desktop/How-to-Improve-Query-Reference-performance-for-large-tables...

https://blog.crossjoin.co.uk/2016/11/20/referenced-queries-and-caching-in-power-bi-and-power-query/

Thanks,
Xi Jin.

[SebSchoon1]

Hello, does it work if the query has been made of table combined of 12 files of around 300 mega each?