# 2.5 The Cost of Fame (Maintenance) ![The Grumpy Elephant](Postgres/assets/arch_index_maintenance.png) In the database warehouse, everyone wants your attention. If you are a popular table, you probably have half a dozen maps (indexes) pointing to you. The Mouse Librarian has a map of your IDs, the Scavenger Bird has a map of your labels, and the Scent Tracker mouse is follow your trail through the web. But fame comes with a heavy tax. ## The Synchronous Squeeze When the Lazy Elephant decides to add a new suitcase to the warehouse (an `INSERT`), or move an old one (an `UPDATE`), he can't just drop the data and head back to his hammock. He is legally required to wait while every single map-maker in the building updates their records. This process is **synchronous**. If you have 10 indexes, the elephant must stand there, tapping his foot, while 10 different animals scribble furiously in their notebooks. This is why adding "just one more index" can suddenly make your database feel like it's wading through cold molasses. ## The Speedy Pass: HOT Optimization The elephant, being fundamentally lazy, has found one brilliant way to cheat: **HOT (Heap Only Tuples)**. Imagine the elephant just wants to change the color of a sock inside a suitcase. If the index only cares about the **Suitcase ID**, and the elephant can fit the new version of the suitcase on the same [[Postgres/Structures/Page|Page]] (the same shipping container), he doesn't tell the Librarian anything. Instead, he leaves a tiny "Forwarding Address" on the old suitcase. When the Librarian eventually follows his map to the old spot, he sees the note, hops over to the new suitcase, and finds the data. This "HOT update" is lightning fast because none of the map-makers have to touch their notebooks. ## When the Tax Man Cometh However, if you change a column that is _actually on the map_ (like changing the Suitcase ID itself), or if the shipping container is full, the shortcut fails. The tax man arrives, and the elephant must wait for the rewrite. Indexes are miracles for reading, but they are weights for writing. Choose your fame wisely.