Three designs against tripwires
Which design earns its cost, and when
teaching load: 2M rows/day, 231 writes/s peak, analytics off the warehouse, data in-country
design
green while
tripwire that flips it
price of the design
single-node + standby
start here
writes, size, ops cost green
at 2M/day with headroom
sustained writes past 5k/s
or data past 3x RAM
cheapest to run and debug
harder migration later
primary + read replicas
read scale + AZ survival
reads fan out, one AZ can die
primary still takes all writes
same write tripwire as above
replicas never buy writes
replica boxes + lag watch
stale-read contracts needed
sharded
only past the tripwire
write cell stays green
past any single writer
earned by a crossed number
never by fashion
ops cost highest: rebalance,
hot keys, cross-shard queries
answered once, not per row: analytics always reads the warehouse, residency is placement in-country
legend: green = start, blue = read scale, peach = paywalled write scale, yellow = one-time answers