Pipelining is primarily a network optimization. It essentially means the client buffers up a bunch of commands and ships them to the server in one go. The commands are not guaranteed to be executed in a transaction. The benefit here is saving network round trip time for every command. 


Redis is single threaded so an *individual* command is always atomic, but two given commands from different clients can execute in sequence, alternating between them for example.

Multi/exec, however, ensures no other clients are executing commands in between the commands in the multi/exec sequence. 

I&#39;m having problems posting JSON with UTF-8 encoding using RestTemplate. Default encoding for JSON is UTF-8 so the media type shouldn&#39;t even contain the charset. I have tried to put charset in the MediaType but it doesn&#39;t seem to work anyway.

My code:

    String dataJson = &quot;{\&quot;food\&quot;: \&quot;sm&#246;rrebr&#246;d\&quot;}&quot;;
    HttpHeaders headers = new HttpHeaders();
    MediaType mediaType = new MediaType(&quot;application&quot;, &quot;json&quot;, StandardCharsets.UTF_8);
    headers.setContentType(mediaType);

    HttpEntity&lt;String&gt; entity = new HttpEntity&lt;String&gt;(dataJson, headers);
    RestTemplate restTemplate = new RestTemplate();
    ResponseEntity&lt;Boolean&gt; formEntity = restTemplate.exchange(postUrl, HttpMethod.POST, entity, Boolean.class);


How can I tell RestTemplate to POST with UTF-8 encoding?

I can give the height element of style numeric values such as `40` but these are required to be integers. How can I make my component to have a height of `100%`?

Setting component height to 100% in react-native

When we use a transaction in Redis, it basically pipelines all the commands within the transaction. And when EXEC is fired, then all the commands are executed together, thus always maintaining the atomicity of multiple commands.

Isn&#39;t this same as pipelining?  

How are pipelining and transaction different?
Also, why does not the single threaded nature of Redis suffice? Why do we explicitly need pipelining/transaction?

pipelining vs transaction in redis

When we use a transaction in Redis, it basically pipelines all the commands within the transaction. And when EXEC is fired, then all the commands are executed together, thus always maintaining the atomicity of multiple commands.
Isn't this same as pipelining?
How are pipelining and transaction different?
Also, why does not the single threaded nature of Redis suffice? Why do we explicitly need pipelining/transaction?

Let&#39;s say we have a User, Wallet REST microservices and an API gateway that glues things together. When Bob registers on our website, our API gateway needs to create a user through the User microservice and a wallet through the Wallet microservice. 

Now here are a few scenarios where things could go wrong:

- User Bob creation fails: that&#39;s OK, we just return an error message to the Bob. We&#39;re using SQL transactions so no one ever saw Bob in the system. Everything&#39;s good :)

- User Bob is created but before our Wallet can be created, our API gateway hard crashes. We now have a User with no wallet (inconsistent data).

- User Bob is created and as we are creating the Wallet, the HTTP connection drops. The wallet creation might have succeeded or it might have not.

What solutions are available to prevent this kind of data inconsistency from happening? Are there patterns that allow transactions to span multiple REST requests? I&#39;ve read the Wikipedia page on [Two-phase commit](http://en.wikipedia.org/wiki/Two-phase_commit_protocol) which seems to touch on this issue but I&#39;m not sure how to apply it in practice. This [Atomic Distributed Transactions: a RESTful design](http://ws-rest.org/2014/sites/default/files/wsrest2014_submission_7.pdf) paper also seems interesting although I haven&#39;t read it yet.

Alternatively, I know REST might just not be suited for this use case. Would perhaps the correct way to handle this situation to drop REST entirely and use a different communication protocol like a message queue system? Or should I enforce consistency in my application code (for example, by having a background job that detects inconsistencies and fixes them or by having a &quot;state&quot; attribute on my User model with &quot;creating&quot;, &quot;created&quot; values, etc.)?

Transactions across REST microservices?

I am trying to create a view where I save an object but I&#39;d like to _undo_ that save if some exception is raised. This is what I tried:

    class MyView(View):
    
        @transaction.atomic
        def post(self, request, *args, **kwargs):
            try:
                some_object = SomeModel(...)
                some_object.save()
    
                if something:
                    raise exception.NotAcceptable()
                    # When the workflow comes into this condition, I think the previous save should be undone
                    # What am I missing?
    
            except exception.NotAcceptable, e:
                # do something

What am I doing wrong? even when the exception is raised `some_object` is still in Database.

Django - Rollback save with transaction atomic

Is `@EnableTransactionManagement` required in Spring Boot?
I did some research. Some folks say you don&#39;t need it, as Spring Boot has it already enabled, others say you do have to use it explicitly. So how is it?


@EnableTransactionManagement in Spring Boot

Node.js 7 and up already support async/await syntax. How should I use async/await with sequelize transactions?

Node.js 7 how to use sequelize transaction with async / await?

I&#39;m developing my insight about distributed systems, and how to maintain data consistency across such systems, where business transactions covers multiple services, bounded contexts and network boundaries.

Here are two approaches which I know are used to implement distributed transactions:

- 2-phase commit (2PC)
- Sagas

2PC is a protocol for applications to *transparently* utilize global ACID transactions by the support of the platform. Being embedded in the platform, it is transparent to the business logic and the application code as far as I know.

Sagas, on the other hand, are series of local transactions, where each local transaction mutates and persist the entities along with some flag indicating the phase of the global transaction and commits the change. In the other words, state of the transaction is part of the domain model. Rollback is the matter of committing a series of &quot;inverted&quot; transactions. Events emitted by the services triggers these local transactions in either case.

Now, when and why would one use sagas over 2PC and vice versa? What are the use cases and pros/cons of both? Especially, the brittleness of sagas makes me nervous, as the inverted distributed transaction could fail as well.

2PC vs Sagas (distributed transactions)

We are defining an architecture to collect log information by Logstash shippers which are installed in various machines and index the data in one elasticsearch server centrally and use Kibana as the graphical layer. We need a reliable messaging system in between Logstash shippers and elasticsearch to grantee the delivery. What factors should be considered when selecting Redis  over RabbitMQ as a data broker/messaging system in between Logstash shippers and the elasticsearch or  vice versa?

Redis Vs RabbitMQ as a data broker/messaging system in between Logstash and elasticsearch

I was wondering what characters are considered valid in a Redis key. I have googled for some time and can not find any useful info.

Like in Python, valid variable name should belong to the class `[a-zA-Z0-9_]`. What are the requirements and conventions for Redis keys?

Naming Convention and Valid Characters for a Redis Key

I understand redis sentinel is a way of configuring HA (high availability) among multiple redis instances. As I see, there is one redis instance actively serving the client requests at any given time. There are two additional servers are on standby (waiting for a failure to happen, so one of them can be in action again). 

 
 - Is it waste of resources? 
 - Is there a better way of using full use of the resources available?
 - Is Redis clustering an alternative to Redis sentinel?

I already looked up redis documentation for [sentinel][1] and [clustering][2], can somebody having experience explain please.

![Master slave configuration in Redis sentinel - before failure][3]


![Master fails and slave kicks in to action][4]


**UPDATE**

OK. In my real deployment scenario I have two servers dedicated for redis. I have another server my Jboss server is running. The application running in Jboss is configured to connect to redis master server(M). 

*Failover scenario*

Ideally, I think when Master cache server fails (either Redis process goes down or machine failure) the application in Jboss needs to connect to Slave cache server. How would I configure the redis servers to achieve this? 

    +--------+          +--------+
    | Master  |---------| Slave  |
    |         |         |        |
    +--------+          +--------+

    Configuration: quorum = 1

  [1]: http://redis.io/topics/sentinel
  [2]: http://redis.io/topics/cluster-tutorial
  [3]: http://i.stack.imgur.com/Citcm.png
  [4]: http://i.stack.imgur.com/CHHzq.png
  [5]: http://www.symantec.com/connect/blogs/configuring-redis-high-availability

Redis sentinel vs clustering

I want to build my PHP-FPM image with `php-redis` extension based on the [official PHP Docker image](https://registry.hub.docker.com/_/php/), for example, using this Dockerfile: [php:5.6-fpm](https://github.com/docker-library/php/blob/a413eb0123d10321928696ffea7442bed7dc0dc7/5.6/fpm/Dockerfile).

The docs say that I can install extensions this way, installing dependencies for extensions manually: 

    FROM php:5.6-fpm
    # Install modules (iconv, mcrypt and gd extensions)
    RUN apt-get update &amp;&amp; apt-get install -y \
            libfreetype6-dev \
            libjpeg62-turbo-dev \
            libmcrypt-dev \
            libpng12-dev \
        &amp;&amp; docker-php-ext-install iconv mcrypt \
        &amp;&amp; docker-php-ext-configure gd --with-freetype-dir=/usr/include/ --with-jpeg-dir=/usr/include/ \
        &amp;&amp; docker-php-ext-install gd
    CMD [&quot;php-fpm&quot;]

Without Docker I installed it with `apt-get install php5-redis`. But how can I install it using the approach above?


How to install php-redis extension using the official PHP Docker image approach?

I&#39;m using Redis 2.8 on Windows which I downloaded from github release. After unzip and I&#39;ve set maxheap in `redis.windows.conf` file. After running `redis-server redis.windows.conf` I get `# Creating  Server TCP listening socket *:6379:No such file or directory`, but redis is not running correctly. I don&#39;t know why.

Content Type	Original Author	Original Content on Stackoverflow
Question	Manas Saxena	View Question on Stackoverflow
Solution 1 - Transactions	The Real Bill	View Answer on Stackoverflow

pipelining vs transaction in redis

Transactions Problem Overview

Transactions Solutions

Solution 1 - Transactions

Setting component height to 100% in react-native

How can I tell RestTemplate to POST with UTF-8 encoding?

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