>So we have another nasty problem here. How much time would the full search take? And would it hamper the performance of other userrs?

If a full search means to do something like searching for a certain string inside the entire table, without using any index, this is something that can easily bring the server down. So, yes, it would affect everyone.

I am looking at alternatives to answer this type of request. For example, maybe we can force a maximum timeframe of 6 to 12 months, in another type of search, just to look a string as is in the table.