You found out through EXPLAIN ANALYZE that your queries are suboptimal. What are the most common causes of query inefficiency?

The most common causes of suboptimal SQL queries:

• Lack of or incorrect use of indexes. Queries without indexes lead to full table scans (Seq Scan), which slow down execution.
• Incorrect JOINs or excessive joins. Complex or inefficient joins can create large intermediate data sets.
• Selecting unnecessary columns or rows. Using SELECT * instead of specific fields, lack of filters.
• Using functions in WHERE conditions that hinder index usage. For example, WHERE LOWER(column) = 'value' without a corresponding index.
• Poor statistics and outdated plans. Statistics need to be updated for the optimizer.
• Incorrect use of subqueries and CTEs. Sometimes they lead to repeated execution.

For optimization, analyze plans, add indexes, rewrite queries, and update statistics.