Max limit for pickerFieldCustom

Below points might improve the performance while dealing with large DataSubSet;
1. In the 'suggestFunction' a condition something like 'Hit DB only if the character count in the search string is greater than or equal to a fixed number' (say 3). This reduces the number of records that return from DB as it uses more characters to match. When the character count is less than 3, return an empty array and include a message something like 'Type in atleast 3 character to search' for 'instructions' attribute of the picker field.
2. Indexing the column in DB which is used to compare might improve the performance.

Depending on the actual use case I suggest to limit the number of rows is the suggestion list to between 10 and 20.

Regarding the Max Limit for Labels and Identifiers, I would agree with stefanh791, as anything more than that number will overload the UI. Just in case if user wants to see more number of suggestions, a selectable grid with filter might fulfil the need.

Agree with the selectable grid with filter in this case. We have found that when the options available to users become too large that they need (a) more information to explain each option which can be solved with more columns in a grid and/or (2) filter/search fields to limit the options.

I had a similar use case, where in I had to fetch from 2000 records. I opted for selectable grid based on the search results, by providing search results below the grid. Appian also recommends to use custom picker only if it is less than 100.

Thanks all, I will give a try with selectable grid with filter.

is there is an option access the search string in pickerfieldcustom