Module subquery 

Subquery merging and unnesting Subquery Operations Module

This module provides functionality for optimizing subqueries:

• Merging derived tables into outer queries
• Eliminating subqueries by converting to CTEs
• Unnesting correlated subqueries

Ported from sqlglot’s optimizer/merge_subqueries.py, eliminate_subqueries.py, and unnest_subqueries.py

Functions

eliminate_subqueries

Eliminate derived tables by converting them to CTEs.

is_correlated

Check if a subquery is correlated (references outer query tables)

is_mergeable

Check if an inner select can be merged into an outer query

merge_subqueries

Merge derived tables into outer queries.

unnest_subqueries

Unnest correlated subqueries where possible.