Processing iterative query constructs in relational databases

An apparatus for functionally rewriting iterative queries for a relational database management system (RDBMS), the apparatus comprising:

• a memory storing instructions;
• and
• at least one processor in communication with the memory, the at least one processor configured, upon execution of the instructions, to perform the following steps:
• receiving a first iterative query, the first iterative query having a first non-iterative part that defines a first main table and a first iterative part that generates values in rows of a first working table based on values in rows of the first main table;
• determining that the first iterative part modifies all of the rows of the first working table;
• and
• rewriting the first iterative part including:
• adding a renaming operation to rename the first working table to produce a new first main table and to rename the first main table to produce a new first working table;
• adding a first delete operation to delete each row of the new first working table;
• and
• adding a first loop operation to repeat the first iterative part until a first termination condition is met.

A non-transitory computer-readable storage medium storing computer instructions for functionally rewriting iterative queries for a relational database management system (RDBMS), that configure at least one processor, upon execution of the instructions, to perform the following steps:

• receiving a first iterative query, the first iterative query having a first non-iterative part that defines a first main table and a first iterative part that generates values in rows of a first working table based on values in rows of the first main table;
• determining that the first iterative part modifies all of the rows of the first working table;
• and
• rewriting the first iterative part including:
• adding a renaming operation to rename the first working table to produce a new first main table and to rename the first main table to produce a new first working table;
• adding a first delete operation to delete each row of the new first working table;
• and
• adding a first loop operation to repeat the first iterative part until a first termination condition is met.