Understanding prefix query searching

[Rupert Fiasco <ru...@gmail.com>]

So I tried to look on google for an answer to this before I posted
here. Basically I am trying to understand how prefix searching works.

I have a dynamic text field (indexed and stored) "full_name_t"

I have some data in my index, specifically a record with full_name_t =
"Robert P Page"

A search on:

full_name_t:Robert

yields that document, however a search on

full_name_t:Robert*

yields nothing.

Why?

To get around this I am doing something like

(full_name_t:Robert OR full_name_t:Robert*)

But I would like to understand why the wildcard doesnt work, shouldn't
it match anything after the first characters of "Robert"?

Thanks

-Rupert