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Order collection after filter?

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Posted on by MarcelLee

Hello,

Can I be sure that the order of the filtered elements of collection Filter(...) will be the same as when it was created ClearCollect(SortByColumns(...))?

Regards,

MarcelLee

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dinusc Microsoft Employee on at

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Hello @MarcelLee,
Can you please clarify the intended behavior? The formula from your message does not seem to be correct.
Generally, when you're pulling a sorted list which contains identical items then the order of those identical items is not guaranteed. You will have to also sort by other columns. Example:
If your formula is ClearCollect(ColName ,SortByColumns( MyTable, "aaa", Ascending))
... and MyTable contains identical values in the "aaa" column then the order of those values in the ColName will not be guaranteed. In order to get the expected order, you will also have to sort by another column (ID or DateCreated for example).
MarcelLee 35 on at

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Hello @dinusc

Of course I make mistake in my quasi formulas.

During the application startup I caching the contents of the SQL table in the collection using the function:
ClearCollect( collectionName; SortByColumns( sqlTableName; "columnA"; SortOrder.Ascending; "columnB"; SortOrder.Ascending; "columnC"; SortOrder.Ascending; "columnD"; SortOrder.Ascending; "columnE"; SortOrder.Ascending; "columnF"; SortOrder.Ascending; "columnID"; SortOrder.Ascending ) )
Later, depending on the context, I filter this collection using the fliter function.
Filter( collectionName; columnD = x )
My question is:
Will I be 100% sure of order filtered elements of collection if I sort (in deterministic way) elements of collection when I create?

The sort function is fully deterministic because the last criterion is the columnID (primary key) in the SQL table.

Regards,
MarcelLee
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dinusc Microsoft Employee on at

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Yes. The sorting order will be consistent with the formula provided.
BTW, the consistency will most likely be guaranteed by the SQL Server, not PowerApps, because the SortByColumns function is delegable which means it will be run on the server *not on the PowerApps client). Please see this for more details: https://docs.microsoft.com/en-us/powerapps/maker/canvas-apps/delegation-list