Delegation on new Table() unions

[BCLS776]

Hi All,

@Shanescows put out a great video today showing some union capability with the Table() function. Great stuff for dropdowns/comboboxes that need an extra choice or two.

However, I am running into some sort of delegation issue even while prefiltering the items in this code:

With({aFilter: Filter(Equipment, IsTrailer = true)},
    Table(
        aFilter,
        {UnitID: "Other"}
    )
)

The code is used in an Items property for a combobox to add an "other" choice in addition to the existing ones in the list. It triggers a delegation warning on aFilter:

The Table() function documentation has no mention of what the truncation limit might be. However, I would not expect this function to be delegated, so does anyone know if this is a platform glitch or a valid warning?

TIA,

Bryan

[LaurensM · Accepted solution]

Hi @BCLS776,

Thanks for sharing these findings! I was very much looking forward to the new Table() function as well and will make a dedicated blog post this week on this new functionality. 😁

When testing the Table function, I did not run into any query condition delegation issues. Delegable query conditions remained delegable and vice versa for non-delegable queries (as expected). One thing to note is that - similar to non-delegable queries and storing data in memory - each individual query within the Table function only returns up to the number of rows defined in the Data Row Limit. In other words, delegable query conditions remain delegable (query is delegated to the server & returns records that match the condition) but the output is subject to the Data Row Limit (max record count returned).

I understand the confusion since this Data Row Limit would already apply due to the With scope variable that pulls your filter output in app memory. Table seems to throw the same warning when using a collection instead of a With function variable as input.

@CarlosFigueira would it be correct to assume that the warning is redundant in case of in-memory table inputs (Data Row Limit already applies) or is the warning being displayed for a specific truncation limit?

If this solves your question, would you be so kind as to accept it as a solution & give it a thumbs up.

Thanks!

[CarlosFigueira · Accepted solution]

@LaurensM you are correct - the warning is indicating that the data row limit applies to each argument to the Table function. For example, in this expression:

Table(Filter(Equipment, IsTrailer = true), {UnitId: "Other"})

If there are more than 500 (or whatever the data row limit is) items in the Equipment table with IsTrailer = true, then only the first 500 would be added to the resulting table, which would have 501 items. There are some ideas on how we can make it delegated, but as far as I know there are no immediate plans to do so.

The case with the With function is interesting. As you said, it already breaks delegation - but there are no warnings for that, which is bad. I'll raise this issue with the team to either properly delegate it, or to notify the maker that the result of that expression would not be further delegated (the expression itself is delegated, though).

[LaurensM]

Thanks for the clarification & swift response @CarlosFigueira! 😊

[PhilJN]

I found this thread while trying to see why I was also getting delegation warnings despite using the function with collections. 

How come there's a row limit being applied at all? Is this just a limitation of the function? I feel like I'm missing something as I thought that delegation only applied to externally acquired data but I'm working with data that's 'in memory'. 

The data row limit says it governs how many rows are retrieved from 'server based connections' which is not something I'm asking the Table function to do, so why does this data row limit factor at all in its use? 

[wmeyer2022]

I'm now getting a delegation warning when using the new table union functionality as well.

My code is:  Table({Manufacturer: "All", ManufacturerID: "0"},dim_Manufacturer)

I'm simply adding an "All" row, and wanted to use this method because adding the All row via a collection would cause delegation issues, so needed to keep my datasource as SQL.

[jaeiow]

All this means is you will only ever get the first 2,000 (what you set) rows.