21 real Data Structures questions from the Redis bank, as asked in Indian campus drives and tech interviews. Every question has a verified answer and an AI-tutor explanation on placd — free to start.
1. What is String?
Junior
A.the most basic Redis value type, a binary-safe sequence of bytes up to 512 MB holding text, numbers, or serialized objects
B.a probabilistic structure that estimates the cardinality of a large set using roughly 12 KB regardless of element count, with about 0.81% standard error
C.an append-only log of entries with unique ids, supporting time-ordered reads, ranges, and consumer groups for messaging workloads
D.a collection of unique members each ordered by an associated floating-point score, enabling fast range and rank queries
A.the most basic Redis value type, a binary-safe sequence of bytes up to 512 MB holding text, numbers, or serialized objects
B.a value type mapping field names to values, ideal for representing a single object with many attributes compactly
C.an ordered sequence of entries implemented as a linked structure where pushes and pops at either end run in constant time
D.a probabilistic structure that estimates the cardinality of a large set using roughly 12 KB regardless of element count, with about 0.81% standard error
A.Hash — an ordered sequence of entries implemented as a linked structure where pushes and pops at either end run in constant time
B.Hash — a probabilistic structure that estimates the cardinality of a large set using roughly 12 KB regardless of element count, with about 0.81% standard error
C.Hash — a value type mapping field names to values, ideal for representing a single object with many attributes compactly
D.Hash — an append-only log of entries with unique ids, supporting time-ordered reads, ranges, and consumer groups for messaging workloads
A.a probabilistic structure that estimates the cardinality of a large set using roughly 12 KB regardless of element count, with about 0.81% standard error
B.the most basic Redis value type, a binary-safe sequence of bytes up to 512 MB holding text, numbers, or serialized objects
C.an ordered sequence of entries implemented as a linked structure where pushes and pops at either end run in constant time
D.a collection of unique members each ordered by an associated floating-point score, enabling fast range and rank queries
A.Sorted set — an append-only log of entries with unique ids, supporting time-ordered reads, ranges, and consumer groups for messaging workloads
B.Sorted set — a collection of unique members each ordered by an associated floating-point score, enabling fast range and rank queries
C.Sorted set — an extension of the string type letting you set, clear, and count individual bits by offset, perfect for compact boolean flags per id
D.Sorted set — a probabilistic structure that estimates the cardinality of a large set using roughly 12 KB regardless of element count, with about 0.81% standard error
A.a probabilistic structure that estimates the cardinality of a large set using roughly 12 KB regardless of element count, with about 0.81% standard error
B.the most basic Redis value type, a binary-safe sequence of bytes up to 512 MB holding text, numbers, or serialized objects
C.an append-only log of entries with unique ids, supporting time-ordered reads, ranges, and consumer groups for messaging workloads
D.an extension of the string type letting you set, clear, and count individual bits by offset, perfect for compact boolean flags per id
14. Which term means: "an extension of the string type letting you set, clear, and count individual bits by offset, perfect for compact boolean flags per id"?
A.the most basic Redis value type, a binary-safe sequence of bytes up to 512 MB holding text, numbers, or serialized objects
B.a probabilistic structure that estimates the cardinality of a large set using roughly 12 KB regardless of element count, with about 0.81% standard error
C.an append-only log of entries with unique ids, supporting time-ordered reads, ranges, and consumer groups for messaging workloads
D.an ordered sequence of entries implemented as a linked structure where pushes and pops at either end run in constant time
17. Which term means: "a probabilistic structure that estimates the cardinality of a large set using roughly 12 KB regardless of element count, with about 0.81% standard error"?
A.HyperLogLog — a collection of unique members each ordered by an associated floating-point score, enabling fast range and rank queries
B.HyperLogLog — a value type mapping field names to values, ideal for representing a single object with many attributes compactly
C.HyperLogLog — the most basic Redis value type, a binary-safe sequence of bytes up to 512 MB holding text, numbers, or serialized objects
D.HyperLogLog — a probabilistic structure that estimates the cardinality of a large set using roughly 12 KB regardless of element count, with about 0.81% standard error
A.an extension of the string type letting you set, clear, and count individual bits by offset, perfect for compact boolean flags per id
B.an ordered sequence of entries implemented as a linked structure where pushes and pops at either end run in constant time
C.a probabilistic structure that estimates the cardinality of a large set using roughly 12 KB regardless of element count, with about 0.81% standard error
D.an append-only log of entries with unique ids, supporting time-ordered reads, ranges, and consumer groups for messaging workloads
20. Which term means: "an append-only log of entries with unique ids, supporting time-ordered reads, ranges, and consumer groups for messaging workloads"?
A.Stream — a value type mapping field names to values, ideal for representing a single object with many attributes compactly
B.Stream — a probabilistic structure that estimates the cardinality of a large set using roughly 12 KB regardless of element count, with about 0.81% standard error
C.Stream — the most basic Redis value type, a binary-safe sequence of bytes up to 512 MB holding text, numbers, or serialized objects
D.Stream — an append-only log of entries with unique ids, supporting time-ordered reads, ranges, and consumer groups for messaging workloads
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