First of all Aware IM will NEVER display or execute a query that goes through thousands of records. It will automatically limit the query to 20 records at a time (or whatever number you indicate in "display items per page").
There is also a way to set minimum length, force the value to be entered etc. You need to define a non-persisted object that would have the attributes that the user would search for. You can then set whatever rules you like for this object - for example, force some attribute to be non-blank. Then you would need to define a process that would look something like this:
ENTER NEW TempObject
DISPLAY ObjectToSearch WHERE ObjectToSearch.Attr1 = TempObject.Attr1 etc
The only problem is that there is currently a bug in Aware IM that prevents queries to use values of temporary objects as described above. We are now looking at this bug and we will post a message on this forum when it is fixed.