I'm looking for a way to do a very simple TTL string in Redis:
So how do I do the equivalent of the following in StackExchange.Redis?
SETEX lolcat 10 "monorailcat"
I found KeyExpire, but that means every key I set needs two calls?
Oops. Never mind:
_Redis.StringSet( "lolcat", "monorailcat", TimeSpan.FromSeconds(10) );
Related
doing a R/W test with redis cluster (servers): 1 master + 2 slaves. the following is the key WRITE code:
var trans = redisDatabase.CreateTransaction();
Task<bool> setResult = trans.StringSetAsync(key, serializedValue, TimeSpan.FromSeconds(10));
Task<RedisResult> waitResult = trans.ExecuteAsync("wait", 3, 10000);
trans.Execute();
trans.WaitAll(setResult, waitResult);
using the following as the connection string:
[server1 ip]:6379,[server2 ip]:6379,[server3 ip]:6379,ssl=False,abortConnect=False
running 100 threads which do 1000 loops of the following steps:
generate a GUID as key and random as value of 1024 bytes
writing the key (using the above code)
retrieve the key using "var stringValue =
redisDatabase.StringGet(key, CommandFlags.PreferSlave);"
compare the two values and print an error if they differ.
running this test a few times generates several errors - trying to understand why as the "wait" with (10 seconds!) operation should have guaranteed the write to all slaves before returning.
Any idea?
WAIT isn't supported by SE.Redis as explained by its prolific author at Stackexchange.redis lacks the "WAIT" support
What about improving consistency guarantees, by adding in some "check, write, read" iterations?
SET a new key value pair (master node)
Read it (set CommandFlags to DemandReplica.
Not there yet? Wait and Try X times.
4.a) Not there yet? SET again. go back to (3) or give up
4.b) There? You're "done"
Won't be perfect but it should reduce probability of losing a SET??
I am using Redis for cache in my application which is configured in spring beans, spring-data-redis 1.7.1, jedis 2.9.0.
I would like to know how to set the race condition ttl in the configuration.
Please comment if you have any suggestions.
If I understand you right, you want the same as that Ruby repo, but in Java.
For that case you may want to put a technical lock key along the one you need.
get yourkey
(nil)
get <yourkey>::lock
// if (nil) then calculate, if t then wait. assuming (nil) here
setex <yourkey>::lock 30 t
OK
// calcultions
set <yourkey> <result>
OK
del <yourkey>::lock
(integer) 1
Here with setex you set a lock key with TTL of 30 sec. You can put another TTL if you want.
There is one problem with the code above - some time will pass before checking a lock and aquiring it. To properly aquire a lock EVAL can be used: eval "local lk=KEYS[1]..'::lock' local lock=redis.call('get',lk) if (lock==false) then redis.call('setex',lk,KEYS[2],'t') return 1 else return 0 end" 2 <yourkey> 30 This either returns 0 if there is no lock or puts a lock and returns 1.
I can't find anywhere online what is default TTL in Redis.
I know that I can set TTL for specific SET, but don't know what is default TTL.
Can someone tell me what default time to live is in Redis?
There is no default TTL. By default, keys are set to live forever.
The keys with no expiration time set will not expire.
If you mean TTL command specifically, starting with v2.8, it will return -2 if no EXPIRE value is set.
Edit:
Itamar Haber's comment is true, I recalled false: There is no such setting in redis config for a global TTL. So I deleted the part about that.
Edit2: Also see the link to the official docs about default expiration of keys here: https://redis.io/commands/expire#appendix-redis-expires
I suppose value set to '-1' by default which means forever.
127.0.0.1:6379> set datakey "my-data"
OK
127.0.0.1:6379> TTL datakey
(integer) -1
127.0.0.1:6379>
REDIS Docs says
Starting with Redis 2.8 the return value in case of error changed:
The command returns -2 if the key does not exist.
The command returns -1 if the key exists but has no associated expire.
The following used to work fine:
redis_client.setex(key, expiry_in_sec, value_json)
And now it suddenly returns:
value is not an integer or out of range
The issue is between the different redis clients.
When working with StrictRedis, the setex syntax is:
setex key, expiry, value
When working with Redis client, the setex syntax is:
setex key, value, expiry
our specific problem was that someone changed the redis client.
Redis will also return this error if the time value (or expiration time) is a float instead of an int.
In my case, using Redis in Python, I had to change the following:
Causes Error
ex = expiration_delta.total_seconds()
Fixed
ex = int(expiration_delta.total_seconds())
success = redis.set(name=redis_key, value=my_val, ex=ex, nx=True)
Note the ex argument to set() makes it work like setex.
I want to implement Absolute and Sliding Caching In Redis. Does anyone have any resource link then it will be helpful
Redis already have many commands for this :
EXPIRE : Set a timeout on key.
EXPIREAT : Same as previous but takes an absolute Unix timestamp (seconds since January 1, 1970).
TTL : Returns the remaining time to live of a key that has a timeout
One important thing you have to know about Expiration on Redis : the timeout value is cleared only when the key is removed or overwritten using SET or GETSET. All others commands (INCR, LPUSH, HMSET, ...) will never change the initial timeout.
Absolute expiration is a native feature of Redis using EXPIRE. To implement a sliding expiration you simply need to reset to timeout value after each command.
A basic way to do this could be
MULTI
GET MYKEY
EXPIRE MYKEY 60
EXEC