|
Maintenance
After a database has been created and all objects
and data have been added and are in use, there will
be times when maintenance must be performed. For example,
it is important to back up the database regularly.
We may also need to create some new indexes to improve
performance. These issues should be taken into consideration
when designing the database to minimize the effect
on users, time taken to perform the task, and effort
involved.
Maintenance design guidelines
include:
Designing your database to be as small as possible
and to exclude redundant information. (We will Normalize
your database which can help you achieve this.) For
example, reducing the size of the database can help
reduce the time taken to back up or, more importantly,
restore a database. This is especially important during
a restore operation because the database is unavailable
while it is being restored.
Designing partitioned tables rather than a single
table, if the table will contain a large number of
rows. For example, a table containing every credit
card transaction received by a bank could be split
into multiple tables, with each table holding data
for a single month. This can ease index maintenance
if new indexes would otherwise have to be added to
improve query performance. It may be necessary to
create the index only on data from the last three
months because older data is no longer referenced.
The larger the table, the longer it takes to create
new indexes.
|
