Hi,

i wish listen your opinions about performance of treatments (AS400/DB2) with this scenario described below:


Imagine that i have a table with 2.500.000 records, the table have indexes created.

I have many aplications batch and interactif that access to this table, always using the key. (the applications are developed with cobol/400)


If i will remove 1.800.000 records from the table (stay with +/- 700.000) do you think that i will win something significant in terms of performance?

If ALL of your queries and ALL of your DML use the indexes so that they only read the exact number of rows they have to, then you will not see any performance gain, because you are at 100% efficiency for the table. This is rare if not unattainable as it is highly unlikely that for every possible query/DML you have an optimal index for it. So reducing the number of rows should provide some sort of performance gain since you will be probably be reading fewer rows somewhere.

Andy