The Relation data type for Perl allows for easy handling and manipulation of database records and tables, providing a powerful tool for data management within the Perl programming language.
This Perl 5 object role represents a Muldis D relation value, with methods that implement all the Muldis D relational operators. Multiple roles (immutable and mutable variants) and bundled Perl 5 classes are available.
However, Set::Relation is still in the experimental stage and may change incompletely between releases. While it is feature complete and fully documented, many functionalities have not been tested in running code, and therefore might be broken. Hence, the module is officially alpha quality and should be used with caution.
To assist in development, help with the test suite is required. Inspired by other Set:: modules and database-related modules is a good starting point to build upon.
In summary, Set::Relation is a wrapper over a set of hash refs, where all the hash refs contain the same number of elements and the same set of hash keys. A Perl hash ref and a Set::Relation object correspond to the relational model concepts of a tuple and a relation, respectively.
This module provides all the standard Set:: operators like 'is_subset,' 'union,' and 'diff.' Moreover, it offers additional operators such as 'join,' 'quotient,' 'projection,' 'group,' 'summary,' 'semijoin,' 'restriction,' 'semidiff,' 'tclose,' and 'outer_join.' By having a hash ref that corresponds to table names and values as Set::Relation objects, you can model an entire relational database.
The name Set::Relation is chosen because 'relation' is a value, same as an integer or an array is a value, and a relation can do everything a generic set can do plus more. Using namespace Set:: reduces confusion with other concepts of the word 'relation', as some people think it means 'compare.'
The SYNOPSIS displays the implementation process of this module with examples.
Version 0.11.1: N/A