Client Server Application Design

Although it is possible to run the applications on the same server as the database, once the database starts to grow it if often wise to move the applications to another machine. The decision to move the application should be based on CPU usage and the memory statistics.

The major bottlenecks on client/server systems is the network and there are a number of areas that should be examined within the application design that reduce this overhead.

	Reduce the quantity of data that is returned to the client i.e. only return what is needed.
	Rather than returning data to the client for processing do the processing at the server by using stored procedures. This not only reduces the data being passed across the network but reduces the processing time at the server as the SPL has already been optimised.
	Increase the size of the FET_BUF_SIZE either across the entire system or on a per sub-process basis. By increasing the FET_BUF_SIZE then the network traffic should decrease particularly if the row size is large.
	Rather that let the application control the referential integrity of the database use referential constraints and triggers on the server. Again this will reduce the volume of the data being transferred between the client and the server.
	Preparing SQL statements requires a transfer between the client and server. If these prepared statements can be re-used then again the network traffic will be reduced.

If the database server has a number of 'hot' areas consider grouping these tables together and move them to different machines. This should ensure the load is balanced across two or more systems.

Shared Memory or TCP/IP connection

There are two fundamental methods of connecting to the server, either shared memory or tcp/ip.

The fastest connection type is shared memory as the messages are placed in and read from memory via the ipc sub-system. But the shared memory segment is not secure as any user can attach to the segment and view or modify the data within it.

Therefore, if a secure mechanism is required the tcp/ip connections should be used.