DB2  Index Design
             Considerations

• Percentage of scan versus update
• Length of scans
• Recovery requirements
• SLA for access
• SLA for update/insert/delete
• REORG impact
• LOAD impact
• PCTFREE
• Low cardinality columns
• Non Unique chains
• Unique requirements (WHERE NOT NULL)
• Extending index for index only access
• Breaking up indexes for Multiple index access
• Indexing Variable length columns

-PADDED or NOT PADDED (V8)

• DPSI versus NPSI
  • Clustering secondary index
  • Drop & rotate partitions
  • Less overhead in Data Sharing
  • Cannot be UNIQUE! – ouch!
• Small tables
• Heavy insert/update windows
• Key length extension 255 to 2000 (V8)
• Sequencing of columns