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>
Related
I need to store the lowest score for each key I add to the set, but when I do ZADD, Redis overwrites the score with the new value even if the score is higher.
ZADD myorderset 1 'one' 2 'two' 3 'three'
(integer) 3
ZRANGE myorderset 0 -1 WITHSCORES
1) "one"
2) "1"
3) "two"
4) "2"
5) "three"
6) "3"
ZADD myorderset 5 'three'
(integer) 0
ZRANGE myorderset 0 -1 WITHSCORES
1) "one"
2) "1"
3) "two"
4) "2"
5) "three"
6) "5"
In the example case, I need the key 'three' not be updated since the new score is higher (5) than the existing (3). Is there a way to do this natively or do I need to create a script in Lua?
I've been researching ZADD modifiers (XX, NX, CH) but none of them do what I need.
Thank you very much!
A Lua script for this CAS use case would be the simplest and idiomatic solution:
127.0.0.1:6379> ZADD myorderset 1 'one' 2 'two' 3 'three'
(integer) 3
127.0.0.1:6379> EVAL "local s = redis.call('ZSCORE', KEYS[1], ARGV[2]) if not s or s > ARGV[1] then redis.call('ZADD', KEYS[1], ARGV[1], ARGV[2]) end" 1 myorderset 5 'three'
(nil)
127.0.0.1:6379> ZRANGE myorderset 0 -1 WITHSCORES
1) "one"
2) "1"
3) "two"
4) "2"
5) "three"
6) "3"
127.0.0.1:6379> EVAL "local s = redis.call('ZSCORE', KEYS[1], ARGV[2]) if not s or s > ARGV[1] then redis.call('ZADD', KEYS[1], ARGV[1], ARGV[2]) end" 1 myorderset 2 'three'
(nil)
127.0.0.1:6379> ZRANGE myorderset 0 -1 WITHSCORES
1) "one"
2) "1"
3) "three"
4) "2"
5) "two"
6) "2"
There is no single command or command option to do it both. You can either use combination of ZSCORE with ZADD(in lua). Alternatively("It is/looks like over-engineered") you may use ZUNIONSTORE with the aggregate option MIN.
With the AGGREGATE option, it is possible to specify how the results of the union are aggregated. This option defaults to SUM, where the score of an element is summed across the inputs where it exists. When this option is set to either MIN or MAX, the resulting set will contain the minimum or maximum score of an element across the inputs where it exists.
127.0.0.1:6379> ZADD base 1 a 2 b 5 c
(integer) 3
127.0.0.1:6379> ZADD new 3 c
(integer) 1
127.0.0.1:6379> ZUNIONSTORE base 2 base new AGGREGATE MIN
(integer) 3
127.0.0.1:6379> DEL new
(integer) 1
127.0.0.1:6379> ZRANGE base 0 -1 WITHSCORES
1) "a"
2) "1"
3) "b"
4) "2"
5) "c"
6) "3"
127.0.0.1:6379> ZADD new 5 b
(integer) 1
127.0.0.1:6379> ZUNIONSTORE base 2 base new AGGREGATE MIN
(integer) 3
127.0.0.1:6379> DEL new
(integer) 1
127.0.0.1:6379> ZRANGE base 0 -1 WITHSCORES
1) "a"
2) "1"
3) "b"
4) "2"
5) "c"
6) "3"
127.0.0.1:6379>
If you prefer,
You may generate new set name with random string in application level
Put EXPIRE to this new set, no need to DEL the new key manually after the ZUNIONSTORE, it will be expired eventually.
It can be done in MULTI/EXEC in a single transaction.
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 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>
As in the doc http://redis.io/commands/sort
SORT mylist BY weight_*
What I would want to do is something like
SORT mylist BY (weight_* + vote_*)
Is that possible to do this just by Redis?
You can use Lua to build each sum_* key and sort by those:
redis 127.0.0.1:6379> sadd myset 1 2 3
(integer) 0
redis 127.0.0.1:6379> mset weight_1 1 weight_2 2 weight_3 3
OK
redis 127.0.0.1:6379> mset vote_1 1 vote_2 2 vote_3 0
OK
redis 127.0.0.1:6379> eval "for i in ipairs(redis.call('smembers', KEYS[1])) do redis.call('set', 'sum_' .. i, redis.call('get','weight_' .. i) + redis.call('get', 'vote_' .. i)) end;" 1 myset
(nil)
redis 127.0.0.1:6379> sort myset by sum_*
1) "1"
2) "3"
3) "2"