DB2 performance tips - PART 1

DB2 Queries that can optimize performance 

1. Select columns which are required
2. Use where clause for queries where ever possible
3. Avoid using NOT in Queries as NOT is non-indexable
4. Use DATE Functions wherever possible to get number of days.
       Eg: Select DATE('25-04-1986') - DATE('04-09-1995')
5. Details on Index and EXPLAIN:

Before and After creating index always use EXPLAIN functionality of DB2 to measure how   and index is working.If the index you created is being used then you will get that in your query once explain runs.

If you want to see when your index is last used you can do that by this query:

SELECT * FROM SYSIBM.SYSINDEXES where NAME = 'your index name';

I will give details on EXPLAIN in my next DB2 blog.