A good IT department always has a complete archiving strategy. It is generally not necessary to keep transactional data available online for long periods of time. In most cases, a 13-month rolling history is all that is necessary. This can and will change from application to application and from company to company. You need a thorough understanding of the application and business rules before making a decision concerning when to archive and how much data to archive. In most cases, you should keep old data available offline in case it is needed. In these scenarios, you should develop a dump-and-purge procedure to export the data to ASCII. This format is always the most transportable in case you change environments or you want to load some of the data into another application such as Microsoft Excel. Always make sure you have a restorable version of the data before you purge it from the database. An archive and purge can dramatically improve performance, since the system has far fewer records to scan when it is searching the tables.
