Composite index leftmost prefix in Python

import sqlite3


def get_indexed_columns(table_name):
    """Simulate a composite index by reading column names that start with 'idx_'."""
    conn = sqlite3.connect(":memory:")
    conn.execute(f"CREATE TABLE {table_name} (id INTEGER, idx_col1 TEXT, idx_col2 INTEGER, other TEXT)")
    conn.execute(f"CREATE INDEX idx_composite ON {table_name} (idx_col1, idx_col2)")
    cursor = conn.execute("SELECT sql FROM sqlite_master WHERE name='idx_composite'")
    index_sql = cursor.fetchone()[0]
    columns_part = index_sql.split("(")[1].rstrip(")")
    columns = [c.strip() for c in columns_part.split(",")]
    conn.close()
    return columns


def matches_leftmost_prefix(available_columns, query_columns):
    """Return True if query_columns form a leftmost prefix of the index columns."""
    if not query_columns:
        return False
    return query_columns == available_columns[: len(query_columns)]


if __name__ == "__main__":
    index_cols = get_indexed_columns("sample")
    print("Index columns:", index_cols)

    test_queries = [
        ["idx_col1"],
        ["idx_col1", "idx_col2"],
        ["idx_col2"],
        ["idx_col2", "idx_col1"],
        ["idx_col1", "other"],
    ]

    for q in test_queries:
        print(f"{q}: {matches_leftmost_prefix(index_cols, q)}")