“This is the second day of my participation in the Gwen Challenge in November. See details: The Last Gwen Challenge in 2021”

String type (string)

  • String type usesetRun the following command to execute the command
    • Store the string set"juejin" "xiaoff"
    • When you want to look up stringsget "juejin"
    • We can also use internally wrapped functions such asSTRLEN
      • STRLEN "juejin"— > 6
  • redisThe string itself can be thought of as an array that can be dynamically expanded
    • For example you can see thatjavaIn theArrayListIn fact, it’s still space for time
    • A fixed length of capacity is allocated firstcapacity
    • The length of the string is calledlengthwhenlengthIs greater thancapacityforresizecapacity
    • At most, each expansion will be expanded1MBThe size of the space, but does not exceed the length of the string512MB

  • You can also set the expiration time
    • ifkeyWill not automatically delete the expiration time
    • It can effectively control cache and improve efficiency
    • expire "juejin" 5
    • Also can useSETEX "juejin" 5 "xiaoff"
    • A littletipsIs that when thek-vIn thevalueIf it is an integer, increment is supported
    • Using theincr {value}

  • In the elimination mechanism itself, all the Settings have been setTime-outKey ‘in a dictionary
    • Lazy delete: Delete it if it expires
    • whileTime to deleteExpired scans are performed every 10 seconds
      • I’ll pick a random number at a timekeyTo delete
      • Actually on the insideredisCan do oneLRUalgorithm
      • Using linked lists willkeyElements are sorted by time

Expired policies will be explained later in conjunction with asynchronous queues and Flush, which are currently described as the base type