DB2 Indexes are taking very large size on disk space I have huge table in DB with estimated size 7 GB  (I saw that using DB2CC and did the action Estimate Size for that Table).

In estimate size dialog I noticed that two of my indexes for that table have very huge size - one is 4 GB and other is 2 GB.

How is possible that index can take so much disk space and is this regular behavior?

Thank you
Indexes essentially duplicate data on disk. The idea though is the tradeoff in performance. Extra disk used, but faster response looking up data.

But since indexes do cost extra disk, one should weigh carefully whether or not the index is actually needed. If not needed, it will cost that extra disk and may even cost you in terms of performance (especially on inserts, updates, and deletes).