Function qualify_column 

pub fn qualify_column(alias: &str, property: &str) -> String

Create a qualified column name for internal DataFusion operations.

Returns format: alias__property (e.g., “p__name”). Both alias and property are normalized to lowercase for case-insensitive behavior.

This is the central utility for creating qualified column names throughout the codebase. All join keys, scan projections, and expression translations should use this function to ensure consistent case-insensitive behavior.

Examples

use lance_graph::case_insensitive::qualify_column;

assert_eq!(qualify_column("Person", "Name"), "person__name");
assert_eq!(qualify_column("p", "fullName"), "p__fullname");