RemoveIF function and PowerApps

[Pfd46995]

Hi Everyone

 I'm very new to PowerApps and I'm trying to get to grips with delegation.  I thought I understood it but in playing around with the RemoveIf function I'm confused.  Perhaps someone could explain the following to me.

I have a test data set consist of 1300 records in a sharepoint list.  I used the RemoveIf function with criteria that I knew would remove 13 records from the sharepoint list based on a common value in of the fields.  This  set of 13 records were located towards the end of the sharepoint list.  Knowing that the delegation limit was currently set to 500 records I fully expected the RemoveIf function not to work (as its non delegatable) thinking that the records I was looking to delete were not in the first 500 records on the list. 

However when I invoked the RemoveIf function it seemed to work.  It deleted all 13 records in the sharepoint list.  I then set the delagation limit to 1 and ran the RemoveIf function again with similar criteria thinking it would only delete one of the 13 records that matched the criteria.  Again it worked, i.e. it deleted all 13 records instead of just one.

I'm hoping somebody could explain to me why this works.  I thought that if a function was non-delegatable then it would only pull in number of records to the delegation limit (in this case 1) and only apply the criteria to that limited set of records.

I hope that makes sense.

many thanks

Paul

[RandyHayes · Accepted solution]

@Pfd46995 

It is all about the criteria you supply as to if delegation will occur.  If your criteria is delegable, then it will do as you see.

Typically, it is best to simply apply the criteria to the ID (primary key) of the datasource.  If you supply that, it will again do as you see.  If you supply criteria that is non-delegable, then you will only apply to x records based on your app settings.

It is almost the same concept as the Filter function.  In a sense, it is not delegable either...it is the criteria you supply as to if it can delegate the filter.  Same happens with the RemoveIf.

But, be cautious with the RemoveIf....it seems to be a shifting outcome.  I have seen completely delegable criteria not do as expected and other times only supplying the primary key to only be successful, and other times the same results you saw.

I hope this is helpful for you.

[Pfd46995]

Thanks @RandyHayes .  That kind of makes sense based on what I've seen  happen.  I feel though that microsoft's documentation around delegation  and RemoveIf is misleading as Microsoft states in their documentation for RemoveIf/Remove

"Delegation

When used with a data source, these functions can't be delegated. Only the first portion of the data source will be retrieved and then the function applied. The result may not represent the complete story. "

which implies that RemoveIF will only ever retrieve the first 500 (or whatever the delegatable limit is set to) records then apply the criteria within the formula.  From I what I've observed this is not true.

Following on I'm interested on what you said about being cautious with RemoveIf.  I've also seen odd results with it as well, that's why I was playing around with it to try and get a better understanding of its behaviour.

In your experience what is the most robust/best way of deleting selected records using powerapps with a sharepoint list?

thank you again

[RandyHayes]

@Pfd46995 

Yes, the docs are a bit misleading and only trying and testing will give you the real story.  

Just keep in mind, the 500 is not a delegation limit, it is a record limit.  It only impacts delegation concerns related to criteria that is nondelegable.  Or in other words, if you can't delegate, then you will only impact x number of records.  If you CAN delegate, you are still limited to x number of records in your results.

So, robust...well, there is none really.  Best way I find is to use the RemoveIf.  Most reliable I find is by providing the primary key (ID) of the record.  It's not fast!

The only other option is to offload it to PowerAutomate.  But then you run into your datasource not being in sync with the actual data without an expensive refresh.  And, the only way to know when to do a refresh would be to wait for the flow to complete and then refresh...this is just dead time for your users - better have a progress icon!!

But, the reality is, the docs are misleading because if you read them the way they are written, it implies that (since the max record limit is 2000), you could never remove a record past 2000.  That would make using PowerApps pretty much worthless with large lists.  So, it should be written to reflect that you can.

[davidmckenzie]

I'm not sure it is down to the criteria supplied, I think it is also down to whether or not the app already has the record loaded.

I have just done a test with delegation limit set to 50 on a list with 150 records and a gallery set to show the list (unfiltered)

• Gallery retrieves 100 records (normal behaviour). Scroll to bottom and last 50 records loaded.
• Clicking a button to RemoveIf on a criteria removed all records with that criteria.
• Refresh datasource so gallery goes back to showing 100 records.
• With only 100 records in the gallery, the same RemoveIf only deletes records in the first 100 rows and doesn't delete from rows 101-150 where the criteria matches.

So it might be the way to get RemoveIf to work reliably is to use - RemoveIf( Filter(datasource, criteria), criteria) since the Filter is delegable and will return everything matching the criteria you want to delete (this does assume your criteria IS delegable).