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H13-711_V3.5 · Question #392

Redis judges whether a key exists using the exist command.

The correct answer is A. True. A is correct because Redis provides the EXISTS command to check whether one or more keys are present in the database. It returns an integer - 1 if the key exists, 0 if it does not - making it the standard and idiomatic way to test key presence in Redis. B is incorrect because…

Big Data Storage Technologies (HDFS, HBase)

Question

Redis judges whether a key exists using the exist command.

Options

  • ATrue
  • BFalse

How the community answered

(55 responses)
  • A
    73% (40)
  • B
    27% (15)

Explanation

A is correct because Redis provides the EXISTS command to check whether one or more keys are present in the database. It returns an integer - 1 if the key exists, 0 if it does not - making it the standard and idiomatic way to test key presence in Redis.

B is incorrect because there is no ambiguity here: EXISTS is a real, documented Redis command and has been part of Redis since version 1.0. There is no alternative command that replaces it for this purpose.

Memory tip: Think of EXISTS as Redis's version of a lookup before you leap - just like checking if key in dict in Python, EXISTS mykey tells you whether something is there before you try to use it.

Topics

#Redis#EXISTS command#Key-Value Store#Key operations

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