If you configure your production database server system appropriately for your client applications, user load, and underlying hardware, maintenance is relatively simple and problem-free.
You can modify the following aspects of a database server relatively easily:
Some configuration changes require you to restart the database server, and some might require you to make a level-0 backup.
Some configuration changes can be made interactively while the database server is in Online mode and then made permanent for the next time the database server is restarted.
You might add coservers either to increase processing capacity temporarily or to increase processing power and expand permanent table distribution.
If you expect to add a fully-capable coserver to extend the table distribution, populating the new coserver dbspaces is easier if large tables use fragmentation schemes that allow you to add data by attaching new fragments.
If you need to redefine the distribution scheme to populate new dbslices or dbspaces, unload data and reload it into the new table definition.
Although tuning applications might require a relatively long development and testing period, putting the changes into effect for users need not require database server downtime.
Application tuning frequently results in dramatic performance improvements. The rule of thumb is the eighty/twenty rule or even the ninety/ten rule, which states that application tuning produces eighty or ninety percent of the performance improvement.
Any change that requires unloading and reloading data is time consuming and difficult. The following actions require the database server to be out of service until changes are complete and backups have been performed:
You must unload table data and reload it into a new table definition to change the distribution method. Although unloading data to an external table and reloading the data into a new definition is relatively efficient, it requires time and other database server resources. It might also require revising views and application programs.
However, if you fragment tables by expression or hybrid expression and hash, you can attach fragments to add new data in an additional expression category or detach fragments that contain data no longer needed.
Except to add or drop chunks for an existing dbspace or to create a new dbspace or dbslice or drop unused spaces, you cannot change the disk layout for existing tables unless you unload all data and reload it into new table definitions that use the new disk layout.
You cannot change the PAGESIZE that you specify when you initialize the database server disk space, unless you unload all table data and reload it into a completely new instance of the database server.
Fundamental changes to the database schema might require changing application programs and views. In addition, the changes themselves reduce efficiency of access to the tables being changed.