Given a hypothetical scenario where a PostgreSQL database is experiencing slow response times for a reporting query. The query involves five table joins (including a many-to-many relationship), usage of several window functions (ROW_NUMBER, RANK), and complex WHERE clauses with OR conditions. Analyze the potential bottlenecks and propose specific optimization techniques. Your response should cover: 1) Indexing strategies appropriate for the joins and filter columns. 2) Rewriting the query to avoid 'OR' conditions in favor of UNION ALL if applicable. 3) Utilization of Common Table Expressions (CTEs) vs subqueries for readability and performance. 4) Explanation of how the query planner might execute the query vs. your optimized version.