# 2.3 BRIN (The Industrial Label)  When the warehouse becomes truly infinite (petabytes of data), even the mouse librarian gets overwhelmed. For these cases, we use a **BRIN** (Block Range Index). ## The Binoculars Approach Imagine a line of massive, identical stone blocks stretching into the distance. Instead of keeping a detailed map of every suitcase, the elephant just sticks a tiny, simple **Yellow Post-it Note** on the side of each block. The note only says two things: "The lowest ID in here is 100, and the highest is 200." When searching for ID 150, the elephant stands far back and uses **Binoculars** to read the post-it notes. If a note says "10-50," the elephant knows it doesn't even need to walk over to that block. It just skips it entirely! BRIN is the ultimate lazy index—it doesn't tell you where something IS, it only tells you where it definitely ISN'T. For the technical manual on BRIN ranges, see the [[Postgres/Structures/Index/BRIN|BRIN Reference]].