DB2 Indexes

Code Example

## DB2 Indexes

Indexes improve query performance by providing fast access paths.

### Create Index
\`\`\`sql
CREATE INDEX index-name
ON table-name (column [ASC|DESC], ...)
\`\`\`

### Index Types

| Type | Description |
|------|-------------|
| Unique | No duplicate keys |
| Non-unique | Allows duplicates |
| Clustering | Determines physical order |
| Partitioned | Matches table partitions |

### When to Create Indexes

1. Primary key (automatic)
2. Foreign key columns
3. Frequently searched columns
4. JOIN columns
5. ORDER BY columns

### When NOT to Index

1. Small tables
2. Frequently updated columns
3. Low cardinality columns
4. Columns rarely in WHERE

### Index Maintenance
Indexes need REORG when fragmented.