Endless feed

  • Build
  • Pixel 07

Difficulty 3 of 5

Readers scroll the newest listings, 4,000 pages/s of 20 items. Sellers add 3 listings/s at the top, and a reader stays about 4 s on each page. Pages time out, and readers see the same listing twice. Keep p99 under 150 ms, errors under 0.1 percent and 0 repeated items.

Play level

HTTP/2SQLMobile users4,000 req/sNode API8 vCPU · 8 GBPostgres2 vCPU · 8 GB
HTTP/2SQLMobile users4,000 req/sNode API8 vCPU · 8 GBPostgres2 vCPU · 8 GB
The board at the start of the level
An index against a full scanTap to add or remove the index

Index · 4 pages read per query · disk writes per insert: 2

Goals and limits

p99 latency
under 150 ms
Error rate
under 0.1%
Duplicates
none
Monthly cost
under 140 USD/mo
Parts you can add
Redis cache, Postgres
Part limit
2
Traffic
4,000 req/s

Concepts

How players did

Player results load from the server.

All levels