Essential Facts about Index Covering in DB2 Universal Database
From the developerWorks archives
Date archived: January 12, 2017 | First published: March 13, 2003
Author Alexander Kuznetsov uses examples to illustrate cases in which adding a column or two to an index can boost a query's performance by "covering" the columns used in a SELECT statement. The DB2 optimizer is very good in recognizing such situations and can choose a very efficient execution plan.
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