flatfile

A flatfile is a plain text file that stores data in a simple, tabular form without the use of a database management system. In its common form, each line represents a record and fields within the line are separated by a delimiter or occupy fixed positions. Flatfiles are designed for straightforward storage and easy interchange of structured data.

Common formats include delimited files such as CSV (comma-separated values), TSV (tab-separated values), and other delimiters, as well as fixed-width files where each field occupies a defined column width. The first line may contain a header that names the fields. Flatfiles are text-based and typically encoded in ASCII or UTF-8 for portability.

Typical uses and advantages: lightweight data exchange between systems, simple configuration files, logs, and archival records. They are easy to view and edit with basic tools and require minimal software. They are broadly supported across programming languages and platforms and can be processed with simple streaming I/O. Limitations include lack of inherent data integrity rules, no built-in querying or indexing, and inefficiency for large datasets or complex data relationships. Concurrency control and schema evolution are also challenging in flatfiles.

In practice, flatfiles are often loaded into a database or parsed by applications to populate structured data stores. They can serve as an interim or supplementary format in ETL pipelines. While modern databases and formats offer richer capabilities, flatfiles remain prevalent for lightweight, interoperable data interchange and simple storage tasks.