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chefe Regular Visitor
Regular Visitor

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

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

 

pq_loading.png

 

 

 

 

 

1 REPLY 1
v-xjiin-msft Super Contributor
Super Contributor

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

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.

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