Autocomplete returns more than X records

Question

I have read How many items in a web form drop down is too many?. I almost agree with Vitaly's answer: no more than 30 (X) items in a drop down. So if auto-complete request returns more than X records, how it can be displayed that it is. For example, item X+1 can display "[show more results..]"or [show next X results] text or something else. And also, how can user return to previous page of results?

  ____________________________
 |  I input Search Text Here  |
 |____________________________|
 | << show previous (10) |     
 |_______________________|
 |    found item 1       | 
 |    found item 2       |
 |     ..                |
 |_______________________|
 |    show next (258) >> |
 |_______________________|

Answer 1

If you are providing an autocomplete field, you are helping your users find information in a long list quickly. Pagination of results obviously doesn't improve the UX because flipping through pages isn't much different from scrolling a regular drop-down list. Therefore, simply don't display any results until there are no more than 10 left (the number may be smaller if the screen's vertical resolution restricts it). This way users will see only the choices most relevant to their query.

Added per comments
It's helpful to display either a message "Too many results" or just the top 10 results before the list is short enough to be helpful to the user. However, unless the searched list contains many items that share 3-4 leading characters, there will be just enough results once 2-3 characters are entered.

Answer 2

Display all the matches. The whole point of the autocomplete is that the user decides when the list is short enough to select one of the items.

To avoid performance problems, you could limit the list at some large number -- say, 200 -- and add an entry at the bottom saying "Too many matches" just in case somebody scrolls to the bottom.

The answers to the How many items in a web form drop down is too many? question are not relevant to this case. They apply to a fixed-size dropdown menu. For an autocomplete, there's no problem having hundreds of entries -- if the user thinks that's too many then they can simply type some more letters to narrow down the list.

Answer 3

It depends on context. I use an autosuggest field in an application to easily search for people in a group by either their name or user id number. The searcher always knows the single item they are looking for, so getting back at most 10 matches lets them quickly select the right one with minimal typing. It also lets them try different spellings.

It might be useful to know to that there are "x more matches" if the short list returned isn't sufficient but it doesn't seem vital because the user keeps narrowing it down. Aside from UX matters, limiting the result set has performance implications for both the server and the client that make it advisable to keep the selection list tight.