What is your experience with PostgreSQL? Have you had to write complex queries or optimize?

I have experience working with PostgreSQL both in writing complex SQL queries and in optimizing performance.

For example, I have created queries with multiple JOINs, subqueries, and window functions for data analytics. I also used CTEs (WITH), aggregate functions, and indexes to speed up data retrieval.

To optimize, I applied EXPLAIN ANALYZE to analyze query execution plans, created and rebuilt indexes, used table partitioning, and optimized queries by reducing the number of scanned rows and avoiding redundant calculations.

An example of a complex query with a window function:

SELECT user_id, order_date, SUM(amount) OVER (PARTITION BY user_id ORDER BY order_date ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS running_total
FROM orders
WHERE order_date >= '2023-01-01';

This experience enables me to work efficiently with PostgreSQL in tasks that require high performance and complex logic.