Memory Block Tracker with Thread Safety | Dataford Interview Questions

Design a system that tracks changed memory address blocks (64-byte blocks); given changed ranges like [1,2],[3,4],[6,9],[10,12], return merged ranges [1,4],[6,12] on query, and make it thread-safe.

Asked in the System coding stage. Treat range endpoints as inclusive block numbers and merge both overlapping and directly adjacent ranges.

Output

Return one row per merged range with merged_start_block and merged_end_block.
Exclude incomplete or invalid ranges, order by merged_start_block ascending, and ensure concurrent sessions use a consistent view.

Schema

changed_memory_ranges

Column	Type	Description
range_idPK	BIGINT	Unique identifier for the recorded changed range
start_block	BIGINT	Inclusive first 64-byte block number
end_block	BIGINT	Inclusive last 64-byte block number

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