Extrapolation of SQL query elapsed response time at application development stage

In a typical database application development, requirement is to optimize SQL queries to meet service level agreements (SLA); the optimized queries are tested on the application development database which is some fraction of the production database. As time progresses the database grows and the earlier optimized queries may not hold SLA anymore. Once the application is launched and deployed, it becomes difficult and expensive to modify the SQL queries. In this paper, we have discussed a model for predicting the SQL query cost and hence the SQL query elapsed response time with the growth of the database at application development time. We have identified and discussed the database statistics which can impact the SQL query cost with increase in the database size and how these can be used to predict ERT. We have tested the model on Oracle 10g and have presented the results in the paper.