Hash Tables and Implementations | Dataford Interview Questions

What is a hash table? What are some common implementations?

Asked in the hiring manager or panel interview stage. For this hands-on SQL exercise, use the supplied reference data to return the common implementations and summarize their documented features.

Output

One row per common implementation, with implementation_name, family, collision_strategy, feature_count, and features.
Include implementations even when no feature record exists. Use 0 and NULL appropriately.
Sort by implementation_name ascending.

Schema

hash_table_implementations

Column	Type	Description
implementation_idPK	INT	Unique implementation identifier
implementation_name	VARCHAR(100)	Name of the hash table implementation
family	VARCHAR(60)	High-level implementation family
collision_strategy	VARCHAR(100)	Method used to resolve collisions
is_common	BOOLEAN	Whether the implementation is considered common

implementation_features

Column	Type	Description
feature_idPK	INT	Unique feature identifier
implementation_id	INT	Referenced hash table implementation
feature_name	VARCHAR(100)	Documented characteristic of the implementation

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