When might you use the REDEFINES clause in a COBOL program?
- To control program flow
- To declare a new variable
- To optimize program execution
- To represent the same data in different formats
The REDEFINES clause in COBOL is used when you want to represent the same data in different formats. It helps conserve memory by allowing different data items to use the same storage space.
What strategies can be employed to handle large datasets with potential duplicate records efficiently in COBOL programs?
- Employ indexing techniques for faster record retrieval
- Implement a hashing algorithm for quick key lookups
- Use sequential file processing for simplicity
- Utilize SORT and MERGE operations to eliminate duplicates
Efficient handling of large datasets with potential duplicates in COBOL involves using SORT and MERGE operations to eliminate duplicate records, ensuring streamlined processing and improved program performance.
What is the purpose of the GLOBAL clause in COBOL for variable declarations?
- It allows variables to be shared among multiple programs
- It defines variables with global visibility
- It enables dynamic memory allocation for variables
- It restricts the scope of variables to the current program
The GLOBAL clause in COBOL is used to declare variables with global visibility, allowing them to be shared among multiple programs. This facilitates communication and data sharing between different program units.
What is the purpose of the relative record number in relative file organization?
- It allows for direct access to records
- It is used for sorting records
- It represents the position of the record in the file
- It uniquely identifies records in a file
The relative record number in relative file organization serves the purpose of allowing direct access to records. It represents the position of the record in the file relative to the beginning, facilitating random access based on the relative record number.
When a CONTINUE statement is encountered, it allows the program to ___________ executing subsequent statements in the same scope.
- Bypass
- Interrupt
- Maintain
- Resume
When a CONTINUE statement is encountered in COBOL, it allows the program to resume executing subsequent statements in the same scope, effectively bypassing the error handling code.
How is an indexed file different from a sequential file in COBOL?
- Indexed files allow direct access to records using a key, while sequential files are accessed sequentially from the start to end
- Indexed files are smaller in size compared to sequential files
- Sequential files are read-only, while indexed files support both read and write operations
- Sequential files are suitable for large datasets, while indexed files are better for small datasets
The primary distinction is that indexed files in COBOL enable direct access to records using a key, offering efficient retrieval based on specific criteria. In contrast, sequential files are accessed sequentially from the beginning to end, making them suitable for large datasets.
In an indexed file system, you notice that certain records are accessed frequently, while others are rarely accessed. How can you optimize the performance of record retrieval for frequently accessed records?
- Clustering frequently accessed records together
- Implementing a multi-level index
- Increasing the size of the index file
- Using alternate indexes
Clustering involves physically arranging records in the file so that frequently accessed records are stored close together. This reduces the number of disk accesses required to retrieve these records, thereby improving performance for frequently accessed data.
_____ is a strategy for handling duplicate records by aggregating data based on a common key.
- Aggregate
- Group By
- Rollup
- Summarize
The Group By strategy in COBOL involves aggregating data based on a common key, allowing for the consolidation and summarization of records with similar key values.
When opening a file in "Output" mode, COBOL will _____ an existing file with the same name.
- Append
- Ignore
- Overwrite
- Rename
When opening a file in "Output" mode, COBOL will overwrite an existing file with the same name. This means that if a file with the specified name already exists, its content will be replaced by the new data.
Which COBOL verb is commonly used to handle file errors and exceptions?
- CONTINUE
- FILE-CONTROL
- HANDLE
- ON EXCEPTION
The FILE-CONTROL verb in COBOL is commonly used to handle file errors and exceptions. It specifies various attributes of files, including the FILE STATUS clause, which helps in managing file-related errors during program execution.