PostgreSQL BRIN Indexes: When & How to Use Block Range Indexes

PostgreSQL BRIN indexes can significantly reduce storage space and improve query performance for range queries on time-series data. They work by storing minimum and maximum values for ranges of consecutive physical blocks. However, they require physical correlation between column values and their position on disk, which may not be ideal for all use cases. Engineers should check correlation for candidate columns and use BRIN indexes when the correlation is above 0.9, and B-tree indexes otherwise. This can help reduce storage space and improve query performance.