A formal analysis of system performance will be carried out later in the Assess Performance task, but it is useful, even at this stage, to spot serious performance problems and adjust the design accordingly. If in doubt about whether there is a performance problem, or whether you have found a solution, do not attempt to change the design yet.
All data structure modifications that move away from the preliminary data structure design will reduce the long-term flexibility of the enterprise's data resource. Moving away from the structure generated from the ERD, by the CASE tool is discouraged. If a different structure is needed, change the CASE model and generate the required structure.
Situations that may cause performance problems include:
* An on-line procedure step that performs a large number of database actions (more than twenty) on each execution
* An index that is subjected to a heavy load of creates and deletes
* A procedure that needs to be executed more than once a second during the peak hour
* A specific record or linkage occurrence that is updated more than ten times per second during some period of the day
* A batch program that updates the database, which is concurrently updated on line
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Activity Overview : A4.10
Stage Overview : Design Stage
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