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Questions tagged [redis]

Redis is an open source, advanced key-value store. It is often referred to as a data structure server since keys can contain strings, hashes, lists, sets and sorted sets.

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1answer
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“Cluster nodes” command showing different status on different Redis Cluster nodes

I had created a redis cluster of 6 instances running on 2 RHEL-7.4 servers some time ago. Today I found that 3 of those instances(on 10.32.129.79) were down. Since I've restarted those 3 instances, I'...
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Redis takes up all the Memory and Crashes

A redis server v2.8.4 is running on a Ubuntu 14.04 VPS with 8 GB RAM and 16 GB swap space (on SSDs). However htop shows that redis alone is taking up 22.4 G of memory! redis-server eventually crashed ...
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Checking status of replication in Redis Cluster

Suppose I have a cluster of 3 master nodes. All the masters have already got a lot of data and now I try to add some nodes as slaves. I want to understand if the new slaves will be ready as soon as ...
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Redis Cluster monitoring

In some limited testing with Redis Cluster I've identified the following conditions where a failed master would be unable to failover: The obvious, all the slaves have failed All of a master's slaves ...
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Order of Execution of Pipelined Commands for Same HashSlot w/ Redis Cluster

So I have a Redis Cluster of n master nodes, and my client connects to some random master node. It then issues a pipelined batch of commands say.. SET {abc}.x 5 SET {abc}.y 3 SET {abc}.z 1 Assume ...
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1answer
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Redis has “commands” that mutate the various data types it can store. Why? Redis is primarily a cache

If you look at something like https://redis.io/commands#list, you will see that types that Redis stores and supports are fully mutable, atomically, within the data store's memory. This does not make ...
2
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1answer
835 views

How to get old and new values on Redis notification?

I need to implement a feature like: once any specific key in Redis is updated, call a C function with the old and new values as arguments. Currently, I know Redis notification and I could use ...
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2answers
651 views

After lowering maxmemory, redis still has high RSS memory

I would like Redis to return some memory. I lowered the maxmemory by 10GB but noticed Redis is still "holding onto it" in RSS based on "used_memory_rss". Based on http://redis.io/topics/memory-...
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1answer
74 views

Read after transaction from secondary session not visible

We've got a database (MySQL ) that has a client 'per channel'. When a player changes channel from, say, 1 to 2, we have to save the state of the player to the database. Saving is done in multiple ...
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0answers
273 views

Redis Performance Optimization - Does a slave's replication take as much compute resources as being a master?

I have the need for two desperate Redis Instances. One's job is mostly as a session store (currently deployed), the others role will be as an usage statistics depot. Assume my servers are single-...
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1answer
782 views

What are 'Range' and 'Radius' queries and what is the difference between them?

While searching for easy and effective tools to improve performance of Data fetching for our application, we bumped into "Redis". In documentation of redis, there is following specific mention of ...
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586 views

What's the best practice when deploying Redis replication cluster on 2 data centers connected by MPLS?

I deployed Redis replication cluster on 2 data centers (ping time between 2 DCs is around 1ms). I used Master (Node1 on DC 1) - Slave (Node2 in DC2) replication model and Sentinel to control ...
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1answer
133 views

Lost persistance in long term in redis without TTL

Our keys are lost in some time and we cannot find the problem. We are using AOF and RDB at the sametime with configs below: RDB: save 900 1 save 300 10 save 60 10000 stop-writes-on-bgsave-error yes ...
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1answer
169 views

Are Delete operations written to AppendOnlyFile in Redis?

AppendOnlyFile in Redis logs every write operation done to the redis database. My Question is that when we delete data from the redis database, are those operations logged in the AppendOnlyFile ? And ...
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redis newbie - how to create hash within a hash?

I want to create this type of a structure in redis: (its basically json data) { "id": "0001", "name":"widget ABC", "model": "model123", "service":"standard", "admin_password": ...
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1answer
210 views

What happens redis uses all allocated memory?

I am quite new to redis and try to learn and explore the structure and architecture of redis. Before version 2.4, there was Virtual Memory option available in redis by which one could swap the ...
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Building Timeline Feature with Complex Post Object Via Mongo and Redis

So I have a scenario where I want to build a timeline for an app. I haven't done this particular thing before, but since I work mostly in mongo my first instinct was to query to get the user's ...
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2answers
92 views

MySQL configure as ACI vs Redis

i have an use case in my application where i need real time communication between users based on their position. Basically one user will create an "event" and it will be sent to near users. On the ...
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0answers
258 views

is there a documented limit to the number of slaves you can have in redis?

I'm trying to find any documentation about the maximum number of slaves you can set up in a redis master / slave configuration. We can potentially have 200 slaves. If there is a limit, I might ...
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514 views

Redis master and slave use different memory

I deployed a redis replica set which consist of one master and one slave. From top command output, I figure out each memory usage. master: 8176352Byte * 8.5% = 678MB slave: 2050116Byte * 75.6% = ...
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0answers
123 views

Redis INCR resetting

We're running a Redis 2.8.4 instance on a Ubuntu 14.04 server where we're experiencing problems with a key that's being reset to 0. It's a key we're only running INCR commands on, but every few ...
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586 views

Redis along with Mysql

I'm currently working on a mobile app alike Google Maps or Wave, but also including parking. The application its running with MySQL primarily. With at this stage most of our data is loaded by python ...
2
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1answer
577 views

Replicating redis foreign table via postgresql synchronous replication

I have synchronous replication between db server, DB1 and DB2. Tested, working. I have a redis server (RD1), integrated with DB1 (master) via redis_fdw, no issues here. I was expecting foreign redis ...
3
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1answer
5k views

Redis remove slave from replication along with sentinel

I have a 3-nodes Redis replication and a 3-nodes Sentinel. I want to remove one slave. I tried stop slave and remove slaveof 10.128.130.139 6379 from configuration. But it became slave again after I ...
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1answer
2k views

Search a Redis Database

Imagine having a tun of hashes in a Redis Database, each representing a user object. How would you get the user with for example the lowest registration date? The user where ts_registered is the ...
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1answer
61 views

Distributing a semi-large key/value list

I have a semi-large (around 30 million records) key/value list which I want to load into redis. The data is stored in PostgreSQL (as master data) and we want to distribute this to clients for faster (...
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256 views

What are the built-in default configuration values of redis.conf?

If I omit a configuration option in redis.conf, what value will be used upon running redis? The self-documented redis.conf states that just rarely. I have found (but didn't try yet) this command: ...
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1answer
359 views

REDIS Bulk RPUSH set values to a list

Is there an optimized way to RPUSH all the values of a set to a list without SPOP-ing them one by one (or SMEMBERS)? (I need to perform bulk RPUSH of huge set each T time to a list) ? Thank you,
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1answer
1k views

How to correctly use PostgreSQL to limit multiple and/or concurrent executions of a task

Let's assume you have a task FOO that can be queued once every minute, and a pool of 50 workers that can be paused. The queue is paused for 10 minutes, and 10 FOO tasks are queued. When the queue is ...
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1answer
210 views

About schema design of NoSQL DB.(How to query multiple data?)

I just got a requirement, to build a web only with Redis. Data of the web is something like this(I write as RDBMS): User Info: user_id,first_name,last_name,age,..... Address: address_id,city,state,...
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1answer
351 views

Master-master database replication on 5 servers

My current project requires immediate replication between 5 databases. Servers are physically distributed across the globe. Currently we use Redis with one master server installed on another 6th ...
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1answer
51 views

Continuous jobs on Redis [closed]

I want to setup a script that sums up a bunch of values in a list and then puts down the result in total-count and then removes the entire list, And this all should be repeated once a minute or as ...