Database / Google Spanner Database Interview questions
Explain the purpose of splits in Spanner?
A split is a contiguous range of rows, ordered by primary key, that Spanner manages as a single unit of data movement and load balancing. Splits are the mechanism behind Spanner's horizontal scalability.
As a table grows or a range of keys gets busy, Spanner automatically divides it into smaller splits and can move individual splits to different servers, spreading both storage and query load across the cluster. Each split is independently replicated using Paxos across the replicas defined by the instance configuration. Good schema design (avoiding hot, sequential keys) matters because it directly affects how evenly splits distribute traffic; a bad key pattern can concentrate load onto very few splits regardless of how many nodes are provisioned.
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