| File Structure Name | Structure Details | Access Method (searching) |
|---|---|---|
| Sequential file | Ordered or unordered records | Sequential access. |
| Partially-indexed file | Ordered records | Sequential access to index, followed by direct access to the first record in the group, then sequential access to find the desired record. |
| Fully-indexed file | Unordered records | Sequential access to the index, followed by direct access to the data file. |
| Direct access file | Unordered or ordered records | A calculationi provides the address (location) of a record, followed by direct access to the record. |
7.1.1 Define the term "key field".
7.1.2 Outline sequential file organization on unordered records and how records can be retrieved by using sequential access via the key field.
7.1.3 Outline sequential file organization on ordered records and how records can be retrieved by using sequential access via the key field.
7.1.4 Outline partially-indexed sequential file organization.
7.1.5 Outline fully-indexed file organization.
7.1.6 Outline direct access file organiation.
7.1.7 Outline the need for fixed and variable-length fields and records, and how they are related to direct and sequential access methods.
7.1.8 Describe the use of hash algorithms to save and retrieve records in a direct access file.
7.1.9 Compare the speed of access and storage requirements for the types of files mentioned in 7.1.2 - 7.1.8.
7.1.10 Explain how the logical organization of data differes from its physical organization.
7.1.11 Outline the need for external sorts.
7.1.12 Demonstrate an understanding of and use the different types of data streams identified in appendix 2.