The company I work at has very specific and unique needs for a help desk system, so none of the open source systems will work for us. That being the case, I created a custom system using PHP and MySQL. It's far from perfect, but it's infinitely better than the last system they were using; trust me! It meets most of our needs quite nicely, but I have a question about the way I have the database set up. Here are the main tables:

ClosedTickets
ClosedTicketSolutions
Locations
OpenTickets
OpenTicketSolutions
Statuses
Technicians

When a user submits a help request, it goes in the "OpenTickets" table. As the technicians work on the problem, they submit entries with a description of what they've done. These entries go in the "OpenTicketSolutions" table. When the problem has been resolved, the last technician to work on the problem closes the ticket and it gets moved to the "ClosedTickets" table. All of the solution entries get moved to the "ClosedTicketSolutions" table as well. The other tables (Locations, Statuses, and Technicians) exist as a means of normalization (each location, status, and technician has an ID which is referenced).

The problem I'm having now is this:

When I want to view a list of all the open tickets, the SQL statement is somewhat complicated because I have to left join the "Locations", "Statuses", and "Technicians" tables. Fields from various tables need to be searchable as well. Check out how complicated the SQL statement is to search closed tickets for tickets submitted by anybody with a first name containing "John":

SELECT ClosedTickets.*, date_format(ClosedTickets.EntryDate, '%c/%e/%y %l:%i %p') AS Formatted_Date, date_format(ClosedDate, '%c/%e/%y %l:%i %p') AS Formatted_ClosedDate, Concat(Technicians.LastName, ', ', Technicians.FirstName) AS TechFullName, Locations.LocationName, date_format(ClosedTicketSolutions.EntryDate, '%c/%e/%y') AS Formatted_Solution_EntryDate, ClosedTicketSolutions.HoursSpent AS SolutionHoursSpent, ClosedTicketSolutions.Tech_ID AS SolutionTech_ID, ClosedTicketSolutions.EntryText
FROM ClosedTickets
LEFT JOIN Technicians ON ClosedTickets.Tech_ID = Technicians.Tech_ID
LEFT JOIN Locations ON ClosedTickets.Location_ID = Locations.Location_ID
LEFT JOIN ClosedTicketSolutions ON ClosedTickets.TicketNum = ClosedTicketSolutions.TicketNum
WHERE (ClosedTickets.FirstName LIKE '%John%')
ORDER BY ClosedDate Desc, ClosedTicketSolutions.EntryDate, ClosedTicketSolutions.Entry_ID

One thing that I'm not able to do right now is search both open and closed tickets at the same time. I don't think a union would work in my case. So I'm wondering if I should store the open and closed tickets in the same table and just have a field indicating whether or not the ticket is closed. The only problem I can forsee is that we have so many closed tickets already (nearly 30,000) so the whole system might perform slowly. Would it be a bad idea to combine the open and closed tickets?