Types of Indexed File

This COBOL system supports more than one type of indexed file. The tables below illustrate the different types available and the features that they support.

Table 1. Indexed Files - Features Supported
  Supports Files Logically >4 Gb Fast Updates on Files with Multiple Duplicate Keys Maximum Occurrences of Duplicate Key Value Support for Variable Length Records and Compression Separate Index File
IDXFORMAT"1" No No 65535 No Yes
IDXFORMAT"2" No No 65535 No Yes
IDXFORMAT"3" No No 65535 Yes Yes
IDXFORMAT"4" No Yes 4 G Yes Yes
IDXFORMAT"8" Yes Yes 4 G Yes No
IDXFORMAT"12" Yes Yes 4 G Yes Yes
Table 2. Indexed Files - Physical Characteristics
  Duplicate Occurrence Records Data Record Alignment File Pointer Size (bytes) Residue Length Field Index Node Includes Record Header
IDXFORMAT"1" No 1 4 n/a No
IDXFORMAT"2" No 1 4 n/a No
IDXFORMAT"3" No 4 4 2 No
IDXFORMAT"4" Yes 4 4 2 No
IDXFORMAT"8" Yes 8 6 4 Yes
IDXFORMAT"12" Yes 8 6 4 Yes