Delegation : It refers to the concept where power apps formulas expressiveness meets the need to minimize data moving over the network. In short, we can say that power Apps will delegate the processing of data to data source instead of moving data to app for processing locally.
Note: Not everything that can be expressed in a PowerApps formula can be delegated to every data source. Please refer the list of delegation here
When we work with large data requires data sources and formulas which can be delegated.
Filter functions that can be delegated.
Aggregate functions : Sum, Average, Min and max can be delegated.
Example : I have created automatically three screen application based on SQL server table.
For Gateway installation or connection follow here
The gallery item property is already set by sortByColumns and search functions which both can be delegated.
If I will search for instance black keyword. The search function will looks everywhere in a text columns. Such as below.
However if I want to search particular records for instance I want to search tile name which contain search team at the right side of tile description. Then in this case I will be using following formula.
Here only Black word which is written on right side is searched as a result.