del a string type(a little value), consume 17 milliseconds, redis version: 3.2.10

[wen...@gmail.com]

so what's happen to this ?

Available since 1.0.0.

Time complexity: O(N) where N is the number of keys that will be removed. When a key to remove holds a value other than a string, the individual complexity for this key is O(M) where M is the number of elements in the list, set, sorted set or hash. Removing a single key that holds a string value is O(1).

i don't understand

[hva...@gmail.com]

You highlighted the part that describes what happens when the key holds a single value (a string) instead of multiple values.  The command has a time complexity of O(N).  A key that holds a single string has one value, so the time complexity is O(1).

[wenk712]

yes，i know that，but del a simple string consume 17 milliseconds 

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[wenk712]

i don't know where the time spent in

[hva...@gmail.com]

Where did you get the 17 milliseconds?  What software gave you the measurement, and exactly how are you sure the measurement didn't include the overhead of making a network connection to the Redis server before sending the command and disconnecting after the reply was received (which is a very common measuring mistake)?

[wenk712]

just get from slowlog command

--

[wenk712]

 SLOWLOG get 5

1) 1) (integer) 0

   2) (integer) 1514406777

   3) (integer) 17048

   4) 1) "DEL"

      2) "user:1000"

[Tuco]

i cannot comment on why it takes 17 milliseconds, but can suggest a way. 

If you are using redis version 4, you can use "unlink" command i think.

However, since you are using 3.2, you can try using "expire <key> 1", it will expire the key after a second, and will be fast i think.

On Sunday, December 31, 2017 at 8:13:38 AM UTC+5:30, wenk712 wrote:

 SLOWLOG get 5

1) 1) (integer) 0

   2) (integer) 1514406777

   3) (integer) 17048

   4) 1) "DEL"

      2) "user:1000"

On Sun, Dec 31, 2017 at 10:40 AM, wenk712 <wen...@gmail.com> wrote:

just get from slowlog command

On Sun, Dec 31, 2017 at 5:52 AM, <hva...@gmail.com> wrote:

Where did you get the 17 milliseconds?  What software gave you the measurement, and exactly how are you sure the measurement didn't include the overhead of making a network connection to the Redis server before sending the command and disconnecting after the reply was received (which is a very common measuring mistake)?

On Friday, December 29, 2017 at 10:40:09 PM UTC-8, wenk712 wrote:

i don't know where the time spent in

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[wenk712]

happened only once so far，i just confused what can lead to this result.   maybe os or jemalloc when deallocation memory occupied by key and value

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