Memoization and Database Concepts | Dataford Interview Questions

Tell me about how memoization works and how it relates to database concepts like caching and repeated subproblems.

Use the provided request and cache records to demonstrate the relationship with SQL. Identify subproblems requested more than once, count their requests and cache hits, and show the cached result when available.

Output

One row per repeated subproblem.
Return subproblem_key, request_count, cache_hit_count, and cached_value.
Include repeated subproblems even when no cache entry exists.
Order by request count descending, then subproblem key ascending.

Schema

memoization_requests

Column	Type	Description
request_idPK	INT	Unique request identifier
subproblem_key	VARCHAR(100)	Inputs identifying a reusable subproblem
cache_hit	BOOLEAN	Whether the request reused a cached result
requested_at	TIMESTAMP	Time when the subproblem was requested

memoization_cache

Column	Type	Description
subproblem_keyPK	VARCHAR(100)	Cache key for a computed subproblem
result_text	VARCHAR(255)	Stored result for the subproblem
computed_at	TIMESTAMP	Time when the cached result was computed

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Problem