I am using Redis queue and adding the data using ListLeftPush and reading data using ListRightPop. It works fine I am able to get the data. But what if data has not popped out? Can we delete old data? or Can we add Value in Redis List with Expiration Time?
How to add time limit for each value while using ListLeftPush command in C#?
It is not possible to add expire time for individual value for the sake of keeping redis simple and fast.
you can only add expire time for individual keys i.e in ur case it is for whole list.
No redis doesn't support that. Expiration is available only for the top level keys. The closes data type/solution for your case would be sorted sets.
You put your expiration time(timestamp) as score while adding to sorted set(ZADD)
Instead of LPOP you use ZPOPMAX to get "to be last expired" element.
Periodically you may use ZREMRANGEBYSCORE to remove expired elements.
For the demonstration i used smaller numbers as expiration dates.
127.0.0.1:6379> ZADD myset 15 "a"
(integer) 0
127.0.0.1:6379> ZADD myset 25 "b"
(integer) 0
127.0.0.1:6379> ZADD myset 35 "c" 45 "d" 55 "e"
(integer) 0
127.0.0.1:6379> ZRANGE myset 0 -1 WITHSCORES
1) "a"
2) "15"
3) "b"
4) "25"
5) "c"
6) "35"
7) "d"
8) "45"
9) "e"
10) "55"
127.0.0.1:6379> ZPOPMAX myset
1) "e"
2) "55"
127.0.0.1:6379> ZREMRANGEBYSCORE myset -1 15
(integer) 1
127.0.0.1:6379> ZRANGE myset 0 -1
1) "b"
2) "c"
3) "d"
127.0.0.1:6379>
Related
I'm trying to strategies how to calculate position/rank based on score and date
I have a two pieces of data with the same score shown in the image below.
If i run the command
$ZADD usersScores 11 userId6
It will add it above userId5 which is not something I want
Is it possible to add it below userId1 maybe based on date?
This is my goal essentially where i would like to show the position based on the amount and the oldest would be ontop via date
Thanks!
Sorted Set ordering
Sorted sets are ordered by their scores first, and then lexigraphically by their members if the scores are equivalent. So in your case if you added the following keys:
127.0.0.1:6379> ZADD myset 11 user1
(integer) 1
127.0.0.1:6379> ZADD myset 11 user5
(integer) 1
127.0.0.1:6379> ZADD myset 24 user3
(integer) 1
127.0.0.1:6379> zadd myset 54 user2
(integer) 1
127.0.0.1:6379> zadd myset 11 user6
(integer) 1
and then did a ZRANGE, you'd get them in ascending order with the members ordered in alphabetical order:
127.0.0.1:6379> zrange myset 0 -1 WITHSCORES
1) "user1"
2) "11"
3) "user5"
4) "11"
5) "user6"
6) "11"
7) "user3"
8) "24"
9) "user2"
10) "54"
What it looks like, is your GUI is using, or are just passing in the rev argument to ZRANGE under the hood, which orders everything in reverse (scores descending, reverse alphabetical)
127.0.0.1:6379> ZRANGE myset 0 -1 WITHSCORES REV
1) "user2"
2) "54"
3) "user3"
4) "24"
5) "user6"
6) "11"
7) "user5"
8) "11"
9) "user1"
10) "11"
Second sort-by
There are a couple of ways you could handle the second sort by with a sorted set, let's assume you wanted to do this with a 32 bit unix timestamp
You could prepend the second sortby field to the member name so if user6's score came in at 1659579650, you'd just make the member name be 1659579650:user1, then when it orders it, it would do so lexigraphically
You could combine the score with the second, since 11 is the score, we could shift 11 32 bits to the left and add/or the timestamp to it, which comes out to 48,904,219,906, those will then order correctly, and then when you want to find the score, all you need to do is right-shift the score by 32 bits.
I need to create a set in Redis:
redis> SADD myset "Hello"
(integer) 1
redis> SADD myset "World"
(integer) 1
redis> SADD myset "World"
(integer) 0
redis> SMEMBERS myset
1) "World"
2) "Hello"
But I need to set expire time for the key myset.
In other words I need a command kind of expire sadd myset... (like SETEX for string values).
Is there any way to execute these commands per one request to Redis server?
There is no built-in command to do this. What you may do is; using transactions. As it is stated in the documentation;
All the commands in a transaction are serialized and executed sequentially. It can never happen that a request issued by another client is served in the middle of the execution of a Redis transaction. This guarantees that the commands are executed as a single isolated operation.
127.0.0.1:6379> MULTI
OK
127.0.0.1:6379> SADD mynewset a b c d e f g
QUEUED
127.0.0.1:6379> SADD mynewset f g h j k l
QUEUED
127.0.0.1:6379> EXPIRE mynewset 86400
QUEUED
127.0.0.1:6379> EXEC
1) (integer) 7
2) (integer) 4
3) (integer) 1
127.0.0.1:6379> TTL mynewset
(integer) 86394
127.0.0.1:6379>
There is also the possibility of using a Lua script to tie the two commands together:
127.0.0.1:6379> EVAL "redis.call('SADD', KEYS[1], unpack(ARGV)) redis.call('EXPIRE', KEYS[1], 3600)" 1 myset a b c d e
(nil)
127.0.0.1:6379> SMEMBERS myset
1) "c"
2) "d"
3) "a"
4) "b"
5) "e"
127.0.0.1:6379> TTL myset
(integer) 3596
I have a redis hash store that looks like Item:<id>, with attribute name. I want to filter the hash store by a prefix for name attribute.
What I'm trying to do is store the name (lowercased) in a separate Z-set called Item:::name while setting the score to 0. By doing this, I'm successfully able to get the desired result using ZRANGEBYLEX however I'm unable to map the results back to the original Items. How should I go about implementing something like this?
I've seen multiple autocomplete examples for Redis which require the same functionality but without linking the words back to an actual Item (hash in this case)
In sorted sets the member can't be duplicated, it has to be unique. So different users with the same name will cause problem.
My suggestion requires application layer coding to parse response array and executing hash commands (it will be like secondary indexes);
127.0.0.1:6379> HSET user:1 name jack
(integer) 1
127.0.0.1:6379> HSET user:2 name john
(integer) 1
127.0.0.1:6379> HSET user:3 name keanu
(integer) 1
127.0.0.1:6379> HSET user:4 name jack
(integer) 1
127.0.0.1:6379> ZADD item:names 0 jack::user:1 0 john::user:2 0 keanu::user:3 0 jack::user:4
(integer) 4
127.0.0.1:6379> ZRANGE item:names 0 -1 WITHSCORES
1) "jack::user:1"
2) "0"
3) "jack::user:4"
4) "0"
5) "john::user:2"
6) "0"
7) "keanu::user:3"
8) "0"
127.0.0.1:6379> ZRANGEBYLEX item:names [jack [jo
1) "jack::user:1"
2) "jack::user:4"
At the end you will have name::hash-key formatted array elements. At application layer if you separate each element to two substrings by using ::(any other string such as !!! or || etc) you will have user:1 and user:4.
127.0.0.1:6379> HGETALL user:1
1) "name"
2) "jack"
127.0.0.1:6379> HGETALL user:4
1) "name"
2) "jack"
127.0.0.1:6379>
I am storing some values in redis like for key: 1 the value will be
{"counter":1,"counter1":2}
Now I need to reset value of counter while the counter1 should be remaining same.
To increase counter I am use the command SETEX mykey 60 redis .
But it will also reset the value of counter1. So is there any way I can reset one value for a single key.
Let me know if I need to add some more info.
Instead of string you may use hash, then it will be easy. you can increment by some other value, delete counter etc etc. Each key in your json will be hash field.
127.0.0.1:6379> hset mykey counter 1 counter1 2
(integer) 2
127.0.0.1:6379> hgetall mykey
1) "counter"
2) "1"
3) "counter1"
4) "2"
127.0.0.1:6379> hset mykey counter 25
(integer) 0
127.0.0.1:6379> hgetall mykey
1) "counter"
2) "25"
3) "counter1"
4) "2"
127.0.0.1:6379> HINCRBY mykey counter 15
(integer) 40
127.0.0.1:6379> hgetall mykey
1) "counter"
2) "40"
3) "counter1"
4) "2"
127.0.0.1:6379>
I am new to sorted sets in Redis (3.0.2). I basically want to update my value in sorted sets of Redis based on unique key. As of now "zadd" each time keeps on adding new values to a specific key.
As of now:
127.0.0.1:6379> zadd xyz 1 "abc"
(integer) 1
127.0.0.1:6379> zadd xyz 1 "newabc"
(integer) 1
127.0.0.1:6379> zrange xyz 0 -1
1) "abc"
2) "newabc"
Required Output: (It should over write the xyz key's value from "abc" to "newabc"
127.0.0.1:6379> zadd xyz 1 "abc"
(integer) 1
127.0.0.1:6379> zadd xyz 1 "newabc"
(integer) 1
127.0.0.1:6379> zrange xyz 0 -1
1) "newabc"
A sorted set in Redis is a set when we talk about the element, while multiple different elements can coexist with the same score.
If you want that output, you'll need to design a different data model, and since I don't know your actual issue or what's your goal in your project, I won't be able to provide a clear solution.