Visualizers
Learn by moving things
Interactive explainers for the ideas behind retrieval, embeddings, and agents. A formula tells you what is true; dragging a vector shows you why. Each one also appears inside the article it belongs to, and runs entirely in your browser, so drag, poke, and break it.
Pull CDN: fill on the first miss
From: CDNs: The Cache Nearest Your Users →A pull CDN is cache-aside at the edge. The first request for a file misses, the edge fetches it once from the origin and keeps a copy, and every request after is a fast edge hit.
First request for this file at the edge: a miss. The edge fetches it once from the origin and keeps a copy on the way back.
Push CDN: pre-stock the edges
From: CDNs: The Cache Nearest Your Users →A push CDN uploads content to every edge at deploy time, before anyone asks. Even the first request in a region is a hit, because you paid the cost up front. Good for high-traffic, stable assets.
At deploy time you upload the file to every edge, before anyone asks for it.
The CDN cache key
From: CDNs: The Cache Nearest Your Users →The cache key decides what counts as the same request. By default it is the whole URL, so ?utm=fb and ?utm=tw become separate copies and wreck the hit rate. Normalize the key to ignore marketing params.
By default the key is the whole URL, so ?utm=fb and ?utm=tw look like different files. Three near-identical requests, three separate copies, a wrecked hit rate.