Hacker News Reader

2 questions: 1) What do they do with the Pinterest-generated ID? Do they store it with each row in addition to the local ID? 2) Why randomly select a shard? Shouldn't you do this based on DB size across all boxes, or at least based on physical space left across all boxes?

View on HN

We decompose 64 bit ids to shard_id, type and local_id. We connect to the shard go to the table and read the local_id.

We randomly select a shard for a new user only. Ofcourse we capacity plan this and open new shards and even out users eventually.

Oops, 1 is directly mentioned in the talk.

Reply on news.ycombinator.com