A sequential data file is a type of file organization in which records are stored in a linear sequence, one after another. This method is commonly used in batch processing, transaction logs, and historical data storage. In a sequential access system, data is read from the beginning of the file until the desired record is found.

Uses a sequential access approach where records are stored and retrieved in order.

Ideal for log files, backup systems, and data archival.

Best suited for batch processing systems where data is processed in bulk.

Supports append-only operations, making it useful for data logging.

Modifying a record requires rewriting the entire file or creating a new file.

Text file

Stores data as plain text, used for logs, CSV files, and structured records.

Binary file

Stores data in binary format, optimizing storage space and increasing processing speed.

Efficient for sequential operations – best for processing large datasets in order.

Simple file structure – no need for complex indexing or database management.

Low storage overhead – does not require extra metadata like indexed file systems.

Well-suited for batch processing – used in payroll processing, inventory tracking, and report generation.

Slow retrieval speed – searching for a specific record requires scanning the entire file.

Difficult updates – modifying a record requires rewriting the whole file.

Not efficient for random access – unlike Indexed file or direct access files, sequential files do not support quick lookups.

Log files – Used in operating systems, web servers, and audit trails.

Transaction processing – Used in banking systems where records are processed in order.

Historical data storage – Used in data warehousing and time-series databases.

Tape storage – Common in backup solutions where data is stored sequentially.

A simple C program to create and read a sequential file:

#include <stdio.h>  

int main() {  
    FILE *file = fopen("data.txt", "w");  
    if (file == NULL) {  
        printf("Error opening file!\n");  
        return 1;  
    }  
    fprintf(file, "1, Alice, 85\n");  
    fprintf(file, "2, Bob, 90\n");  
    fclose(file);  

    file = fopen("data.txt", "r");  
    char line[50];  
    while (fgets(line, sizeof(line), file)) {  
        printf("%s", line);  
    }  
    fclose(file);  
    return 0;  
}

A simple Python script to create and read a sequential file:

# Writing to the file
try:
    with open("data.txt", "a") as file:
        file.write("1, Alice, 85\n")
        file.write("2, Bob, 90\n")
except IOError:
    print("Error opening file!")

# Reading from the file
try:
    with open("data.txt", "r") as file:
        for line in file:
            print(line, end='')  # end='' to avoid adding extra newlines
except IOError:
    print("Error opening file!")

A sequential data file is an efficient and simple file organization method used for processing data in an ordered manner. It is widely used in transaction logs, batch processing systems, and historical data storage. However, it is not suitable for applications requiring random access or frequent record modification.

Besides new line there are other characters which could be used to separate data in a file.

• File system
• Data storage
• Computer file
• Database management system
• Binary file
• Text file
• JSON streaming