nikhilanshuman

 Profile Answers by nikhilanshuman 

• Mar 17th, 2010

 

Summary tables are the tables which contain the summarized or say "Aggregated" data to tune up query performance.

Example :

Suppose that we have a table which contains following columns :
a) Medicine_Name
b) Sell
c) Time

Now, the business requirement is to get the sell of medicine on month basis.  Here if a query is fired to aggregate the medicine cell will have to use aggregation to get the sell monthly each time.

Instead of that if a summary table is created which contains the monthly sell records, the query cost will decrease as the query will directly get the aggregated data from the summary table.

In this scenario, the summary table will contain following columns :

a) Medicine_Name
b) Sell
c) MONTH

Hence, for sell of all days of month,only one aggregated recrd will come in Summary table.i.e. for each month one row will be there in summary table containing aggregated data. This will increase the performance of a query.