Tuna Toksoz 𐰆𐰽𐰀

Typed a Gmail username once and the UI instantly said: “Username already taken.” I asked an ex-Staff Google engineer the same problem (he was director of engineering in a startup i worked at), “You’re not doing an Elasticsearch query on every keypress, right?” He laughed. “No. That’d be a crime.” My classy approach: 1. Keep an in-memory trie of reserved usernames. 2. Update it async (delta pushes), not per keystroke. 3. UI checks locally in O(k) where k = username length. Numbers (why this is feasible): 1. Assume 2B usernames, avg length 10 chars. 2. Raw chars = 2B × 10 = 20B chars. 3. Even if you store 1 byte/char (not true in a trie, but baseline) that’s ~20GB just for characters. 4. A trie is about prefix sharing, so common prefixes collapse hard. Real memory is “nodes + edges”, not “strings”. 5. If we model ~1 node per char worst-case: ~20B nodes. - If a node is 8 bytes (tight packed arrays, bitsets, offset indices; no pointers), worst-case is 160GB. - With prefix sharing, you can easily cut multiples of that depending on distribution (gmail-like usernames are not random). 6. Shard by first 2 chars (36 possible: a-z, 0-9). 36² = 1296 shards. - Worst-case per shard: 160GB / 1296 ≈ 123MB. - Suddenly “instant check” fits in memory per front-end pod or edge POP. Yes, you can also do it with WebSockets: 1. Client streams “candidate username” events. 2. Server replies with availability. 3. Works fine, but now you’ve built a hot, stateful, low-latency service for… a UI hint. Most people will ship: 1. Elasticsearch prefix search. 2. Debounce 150ms. 3. Cache a bit. 4. Pray at peak signup traffic. And it works. But the trie approach is the kind of solution where the UI feels like magic tbh and it's something novel that i thought of. Things are just different at google scale.

Interviewer: If apps like Instagram are free, how do they store billions of photos and videos without charging users anything?

babamı kaybettik kanseri yenemedi başımız sağolsun

Bir admob gelir modeli var şaşırıp kaldım yıllardır sektördeyim bilmediğim o kadar çok şey var ki. Adamlar onboardinge reklam koyuyor, Onboarding devamında dil seçimi ekliyorlar ama onun altındaki buton da admob butonu sanki Continue butonu gibi, yetmiyor her sayfada bir işlem yapılacak gibi gösterip yine admoba yönlendiriyorlar. Bir kullanıcı uygulamanın içine girene kadar(dashboard diyelim) minimum 6 reklama maruz kalıyor. Bu applerin aylık indirmeleri 2-3 milyon. Bir araştıracağm detaylı neymiş bu olay. Sadece abonelik ile gelir yok evet ama ilginçtir 2 milyon indirme yapıyorsun 5K nile gelir yok. Sadece admob kurgusu. Bu indirmeleri nasıl yapıyorsun bu kadar kazanç var demekki admobta. Bu arada kendi applerimde admob var 1 kullanıcıya tek reklam gösterdiğimde reklam giderinin maksimum %5 ini geri getiriyor.

Happy International Women's Day everybody.

🚨 BREAKING: Palo Alto Networks is receiving praise after firing employee Madhu Raju, who recorded himself dancing on the World War II Memorial. The company acted swiftly after the video spread online.