Layer 3 · Go deeper · 6 min
Go deeper
Size it, build it, then make the calls an interviewer will push you on.
Back of the envelope
Size it up
Tap through each step of the arithmetic.
How long does one release take across 500 silos?
Build-up · 6 steps
Promote one tenant from pool to silo
Acme upgrades to the enterprise tier. Its data moves into a fresh silo while its users keep working, and only one step is a sharp switch.
Step 1 of 6
Acme lives in the pool
Acme just bought the enterprise tier. Its rows sit in a shared database of 250 tenants, each tagged with its tenant ID, so they can be found and moved. The router still sends Acme to the pool.
4 interview moments
You’re the candidate
The interviewer pushes on the hard parts. Pick an approach and see how it holds up.
Deep dive 1 of 4
Interviewer
“Your B2B commerce SaaS adds integrations that run customer scripts, plus small config rows. Pool or silo?”
Your move. Pick an approach:
Deep dive 2 of 4
Interviewer
“Your B2B helpdesk SaaS has 2,000 tenants, most of them small. Which shape do you run?”
Assume a $350 floor per silo, and a pool with a $3,000 floor plus $4.50 a tenant.
Your move. Pick an approach:
Deep dive 3 of 4
Interviewer
“One tenant now sends 30% of all queries, and its big sale saturates the shared database. What do you do?”
Your move. Pick an approach:
Deep dive 4 of 4
Interviewer
“You launch with one pooled stamp that easily fits every tenant. Do you run one stamp or two?”
Your move. Pick an approach: