VSAM ESDS and RRDS

Code Example

## VSAM ESDS and RRDS

Entry-Sequenced and Relative Record Dataset types.

### ESDS (Entry-Sequenced)
- Records in arrival sequence
- No primary key
- Access by RBA (Relative Byte Address)
- No deletions (mark as inactive)
- Like sequential file

### ESDS Use Cases
- Log files
- Audit trails
- Historical data
- Journal files

### RRDS (Relative Record)
- Records in numbered slots
- Access by slot number (RRN)
- Fixed-length records
- Empty slots allowed

### RRDS Use Cases
- Hash tables
- Fixed ID systems
- Quick direct access
- Sparse data

### COBOL Access
ESDS: ORGANIZATION SEQUENTIAL
RRDS: ORGANIZATION RELATIVE