Indexes are a fundamental feature of relational databases, and  PostgreSQL offers developers and designers a rich collection of options. To take advantage of these entirely, users need to understand the basic concept of indexes to compare the different index types and apply them to different application scenarios. Only then can you make an informed decision about your database index strategy and design. One thing is for sure: Not all indexes are appropriate for all circumstances, and using a ‘wrong’ index can have the opposite effect to what you intend. Armed with more advanced knowledge, you can avoid this worst-case scenario!