In Jira, list fields have auto-completion.
However, it uses a static data set to suggest the value. It does not handle more than a few thousand entries.
In order for the auto-completion to support tens of thousands of entries to search in, other SaaS products' lists usually issue an Ajax call everytime the field value changes. For exemple:
- nothing happens while the field value is shorter than 3 charactes
- on any change, if the field value length is superior or equal to 3, an ajax call is issued, returning a limited list of results (100 for example) with a flag indicating weither there's more results in store, not returned.
- the auto-completion only works on the list returned by the Ajax call
That would allow lists to have any size, as long as the Ajax call is fast enough to keep usability high.
So, is there any addon already providing that, or where would I start to develop my own feature? Thank you! 
