why filtering the query does not change the volume of data that get loaded?

[osinquinvdm]

In order to make load time faster during the testing phase I'd like to filter the data and work on a subset.

Unfortunately after I applied a filtering criteria that should filter out 80% of the data, I still see that PBI loads the exact same volume of data.

Why is that?

How can I reduce the amount of data I work with during the dev phase (besides exporting to Excel and reimporting a filtered out csv...)

thanks 

[Anonymous]

Hi osqinquinvdm

If you use a DB, please check in the Query Editor, if Query folding is broken.

[ImkeF]

Are you connecting to a SQL-server or what is your data source?

[fiveone]

The source is a simple csv with next to zero processing

[ImkeF · Accepted solution]

Then the filter will not be able to affect the load-process, as no query-folding will take place on this source.

Subsequent calculations should be faster, (but not necessarily, as the commands will be translated to an internal execuation plan that the user cannot influence).

Try using a Table.Buffer for your filter-expression.

[fiveone]

Thanks for your comments. Where can I find further details on that "query folding" aspect

[ImkeF]

This is an excellent article: https://www.mssqltips.com/sqlservertip/3635/query-folding-in-power-query-to-improve-performance/

[Greg_Deckler]

Where are you basing that notion? On the count of rows in the table, on the size of the PBIX file, ?

[fiveone]

on what the pop-up window says and on the time it takes.

thanks for jumping in

[Greg_Deckler]

Might be related to what type of filter you are using. Is it a date field filter? I have seen some weirdness with that. My first question would be, is it really importing everything. So, if you create a quick COUNT aggregation or look at the bottom of Desktop client in the data area, how many rows do you get with and without the filter in the final table? Does it match what is being reported in the pop-up. If those are the same with and without and match the pop-up, then my guess would be that your filter isn't doing what you think it is doing. If the final row counts in the table are different but the pop-up is the same number, then it might have something to do with the date filter weirdness I mentioned.