Building blockOfficial
Pre-Signed Direct Upload
The client uploads to object storage itself with a short-lived signed URL, so large files never pass through the application.
object-storageuploadscdns3
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YouHow should we handle a sudden spike in orders?
CoachA queue can absorb the burst. Let’s discuss latency and failure handling before we update the canvas.
Order APIAccept requests
QueueAbsorb bursts
WorkersProcess orders
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Building blocks, complete architectures, and variations worth comparing. Search by the problem you want to solve or a component you want to understand.
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Building blockOfficial
Reservation with a TTL, and a Unique Constraint
A short-lived hold makes checkout feel fast; a unique constraint in the database is what actually makes double-selling impossible.
bookingconcurrencyinventorypostgresSystem Design AI0 bookmarks0 commentsBuilding blockOfficial
Geospatial Index with TTL
Positions written to a cell-based index with a short expiry, so "who is near me" is a small read and anything that stops reporting disappears on its own.
geospatiallocationh3redisSystem Design AI0 bookmarks0 commentsBuilding blockOfficial
WebSocket Gateway and Session Registry
Dumb servers hold the sockets, a registry maps each online user to the one holding theirs, and the logic lives behind both.
websocketsrealtimepresencechatSystem Design AI0 bookmarks0 commentsBuilding blockOfficial
Delay Queue Scheduler
A table of things due later, a sweeper that claims the ones due soon, and a delay queue that holds each until its moment.
schedulingreminderssqsmessage-queueSystem Design AI0 bookmarks0 commentsBuilding blockOfficial
Idempotency Keys
The caller names the operation, the server stores the first response under that name, and a retry replays it instead of doing the work twice.
idempotencypaymentsretriesexactly-onceSystem Design AI0 bookmarks0 commentsBuilding blockOfficial
Token Bucket Rate Limiter
A bucket of tokens per key, refilled at a fixed rate, with refill-and-take done atomically in one place so every server agrees.
rate-limitertoken-bucketredisluaSystem Design AI0 bookmarks0 commentsBuilding blockOfficial
Hybrid Fan-Out (Push and Pull)
Push new items into followers' timelines at write time, except for accounts with huge followings, whose posts are pulled and merged at read time.
fan-outnews-feedtimelineredisSystem Design AI0 bookmarks0 commentsBuilding blockOfficial
Transactional Outbox
Write the row and the event it should publish in one transaction, then relay the event, so a commit and its message can never disagree.
outbox-patternkafkacdcconsistencySystem Design AI0 bookmarks0 commentsBuilding blockOfficial
Cache-Aside (Lazy Loading)
The service reads the cache first and fills it on a miss, so the cache holds only what is actually asked for and an outage degrades to slow rather than down.
cachingredisread-pathbuilding-blockSystem Design AI0 bookmarks0 comments